Rift S runs at 80hz?.. The quest 2 and rift CV1 run at 90hz!. Don't think there is likely a way of running the rift S at the speed you're looking for that's why you can't find anything.
Well that is something I thought of but not a single mention of that in any review of the update from any site or any youtube channel. All that has been said is that some Quest 2 games will get 90hz updates and then there is the info on using Link to choose 72, 80, or 90 for pc vr games.
With v23 I'm pretty sure that your Q2 will then be native 90Hz by default. Whether or not your games will have a 90Hz option will depend on the game developer.
Before the v23 there was an option in experimental features to enable 90Hz, I think that has now disappeared. So what TomCgcmfc said makes sense.