There is a connection between Orlæg, Wyrd, and Mægen.
Wyrd is the overriding concept. Orlæg is an aspect of Wyrd. Mægen is a separate concept entirely but can overlap with Orlæg mostly but also to a lesser extent general Wyrd.

Wyrd is not predetermined, your fate is not written at birth. Instead, as you proceed through life the choices you make, the choices others make around you, and the circumstances you are born into and proceed through will shape your wyrd. It is more a factor of cause and effect than it is predetermination. Wyrd generally applies as an umbrella term for your fate seen in this way. Your choices affect your destiny.
Orlæg brings a new level to this. Orlæg is also a term for fate, but more specifically it would apply to things not directed by an individual but which still affect them. Bosworth-Toller lists the term “or” as a word for origins, beginnings, early, and even appears as a prefix in that aspect. The rest “-læg” is debatable. I’ve seen “lah” or law as the root because of its variant “lagu”. But the beginning “Or” informs as much as needed for this discussion on Orlæg. This means that Orlæg is then a term for fate, yes, but more specifically fate which comes before; prior fate in a way.
For an example of this, your entire childhood is more or less out of your control. It shapes who you are, what you think and believe, and how you continue to grow later. Your hand is absent from most of those decisions. You cannot choose the manner in which you are raised, nor can you choose who your parents are. Their decisions, their wyrd, follows you eternally as part of your orlæg. It is fate prescribed onto you by the choices of other before you could even have a choice in the matter, it is your Orlæg.
Generally, it is best to stop using Orlæg for events after childhood though. All your ancestor’s deeds, your parents deeds, and your childhood are your orlæg. That which follows all that though you have some control over. Your boss cannot affect your orlæg, your choice to work there overrides. Your spouse cannot affect your orlæg, your choice to marry them overrides. In both cases, even though decisions are made on your behalf, your initial decisions make it wyrd and not orlæg. Your decisions will affect your children’s orlæg though.
Orlæg gets a bit interesting too though. Your physical looks are in effect part of your orlæg. You didn’t choose them but they affect you and your life for as long as you live. My grandparents bought me braces for my teeth specifically in case I became a salesman. They wanted to ensure I had the best opportunity to influence people with a good smile. Braces and makeup and fashion are evidence of this aspect because they superficially gloss over our foundational orlæg. To explain, prettier people have it easier. Their good looks are bestowed on them by their ancestors as a factor of Orlæg. A person doesn’t choose to be born handsome, but that handsomeness will affect their life. The inverse is true. A person with terrible body odor is less likely to be someone you willingly associate with – hygiene helps but doesn’t change the fact such a body odor exists in the first place. The list could go on and on. Basically, we are granted by our ancestors what we end up becoming physically, that’s how DNA works. We can change it some and definitely influence it, but there is a limit. If a person was born very unfortunate looking and changed it later through plastic surgery, their Orlæg hasn’t changed. Their children would still be affected by the lingering Orlæg, furthermore, their world view would still be shaped by their childhood in that situation too. If someone was born barren or infertile, it would be something that they could not change, again orlæg, and that would change their world view. My orlæg has not changed despite braces, I may smile today in an uncrooked manner but my children will inherit what I was born with and not what the orthodontist crafted. Your parent’s wealth is also a factor of Orlæg. You cannot choose to have rich parents, but being born into them substantially changes your life. A person born with both looks and money? They won the jackpot of Orlæg. A person born with neither will have a more difficult life. A person with kind parents? That affects it. A person with cruel parents? That affects it. Your orlæg is shaped by where you came from, it is the culmination of your past, your parent’s past, your far-flung ancestor’s past.
Orlæg is not a conscious choice. Wyrd is a culmination of your consciousness and unconscious choices woven by every decision you or others make pushing you to toward a reaction from those actions. Yet your wyrd will become your children’s orlæg. So wyrd is the umbrella term, it is the cause and effect – action and reaction – which rules our being. Wyrd draws in aspects of our past but also leads us toward our future. You cannot evade your wyrd because you cannot rewrite the choices you have made in the past. You can live the best life you can within the limits of your wyrd though.
Now I will go off on a rabbit trail here for a moment. Magic exists in the Anglo-Saxon context in a cause and effect role as well. That is not something that is chance. Magic to the Anglo-Saxons would have been a way to shift the probability of wyrd in their favor. They wore amulets, they practiced healing spells and curses and charms (many of which have come down to us). Magic exists to shift wyrd in subtle ways. Will Clufweart recover from her sickness? Magic is applied to help shift wyrd in her favor. Will the crops be good this year? Magic is applied to shift wyrd in favor of good growing weather or good germination. This is one reason I would place Frige as a goddess involved with wyrd; she’s a goddess (in other traditions at least, and in ours as well if many people’s views are to be trusted) of magic and if magic is there to shift wyrd, then she’s a supreme shifter of wyrd. There comes a time when no amount of magic can shift wyrd – wyrd is immutable after it is set. You can shift things around a bit when the strings are being laid in, but once laid they become most assuredly fixed. Magic then in an Anglo-Saxon context would not be much less like the Harry Potter kind of flash and oomph and more about fixing probabilities and skewing chances in favor of something or against the favor of something. Magic is in effect the way you guide wyrd several steps out. Beseeching the gods, wights, or ancestors on your behalf is also in effect a similar prospect of hedging on the shaping of wyrd.
Wyrd becomes then this strange concept which is ever-shifting in the future but immutable in the past.
Mægen apples to this concept because your Mægen is a product of your Orlæg and your Wyrd. They overlap, especially with your Orlæg. Your strength will only be what you are capable of, what you are capable of is variable on factors as diverse as how you apply yourself and your in-born potential. No person truly reaches their potential, but they can sure come close. Olympic athletes? Yeah, that’s not the ordinary person, but they have trained to maximize their physical potential and come really close to being as great as people can be, as close to their in-born potential in that one field that they possibly can. The amount of mægen a person develops depends on this potential which depends on your orlæg. That is one overlap.
Mægen is also something less tangible. If my parents were truly terrible people and had made “a bad name for themselves” then when I inherited that name and I met someone they slighted, that name would set me at a disadvantage. If my parents were famous for their kindness, if I met the beneficiary of that kindness then their name may set me at an advantage with that person. My parent’s wyrd, how they moved their mægen, their credits and debts to their name, all of those went into my orlæg which can credit or indebt my mægen in certain settings.
I then propose the following definitions as clarifications of these concepts:
Wyrd: your fate, specifically how your actions and the actions of others affect your future
Orlæg: your fate that has already come to pass, specifically how actions outside of your control (upbringing, ancestors, parents actions) have shaped your wyrd as it is currently unfolding
Mægen: your (physical and metaphysical) strength and life-force, specifically that which is associated with your continued being [obviously more complicated than this]