I'm also curious what the OP really imagines for "true origin" stories. Choosing to be a noble of a great house sounds a lot like Red Prince. But I suppose the OP means you could be any noble, or a beggar, or whatever. Maybe you could lay several small choices of several different events in your past which would influence character responses throughout the game? So, you could be a corrupt merchant who allied with bandits and helped them take over a town, or a honest merchant who sided with the town to fight bandits, or a honest soldier who fought the bandits, or any combination of those aspects, etc.

And, as Stabbey said, these might set up certain set pieces or friends or enemies or events showing up in a modular way. But that all likely would be a massive amount of work for a relatively incoherent experience. Specific character origins that you can shape how you want is both less work, and much more likely to produce interesting stories. The way I see it, the origin stories concept was largely in relation to D:OS1, where you had one possible background as a source hunter. But in D:OS2, you could have 6 or so different origins. So, yes maybe "origin stories" in this case basically means "preset characters," but it's hard to imagine another possibility that would be any good.