Isn't it just the PC version of Xbox games? I believe that is where the confusion comes in.
well yes. but it's not like there's a big difference technically speaking between an Xbox game on a Series X and an Xbox game on the Xbox app on PC.
Windows and Xbox are so intertwined these days that you can actually (with some tinkering) attempt to install Xbox console games on a Windows PC, and it actually will often install and give you a boot screen when you try to start it. the only thing that keeps Xbox One and Series X games from actually booting up is the small differences in the specialised DX11/12 API versions of the Xbox games... and probably some anti piracy measures as well.
a fun example for how close Xbox and PC are these days, that I used as an example in a recent video I made, about why GamePass Core shouldn't exist anymore, is Scorn.
Scorn on Xbox SX had basically no graphics options. it just ran at 4k FSR2 Quality mode, at 60fps... and that's it.
on PC of course there were some PC typical settings, like quality settings, an FOV slider, FPS cap settings etc.
well... people quickly noticed that if you change the FOV in the Xbox PC version, and then launch the game on an Xbox console, your FOV on Xbox consoles would be the same as the one you set on Xbox PC.
but it got even better! if you locked the Xbox PC version to 30fps, then started the game on console, the Xbox console version would be locked to 30fps.
sadly, you couldn't run it at above 60fps on Xbox, because the game ran in a 60hz container, so it forced Vsync to 60hz if you attempted to set the fps limit higher.
but I bet there are more examples like this, where Xbox PC games have settings that are usually unavailable to tweak on Xbox consoles but still influence the Xbox console version when changed.
Doom The Dark Ages has a performance monitor screen where it shows FPS, GPU utilisation etc., and that's another instance where this works. turn then on on Xbox PC, and it will be on on Xbox consoles.