If games like Xenoblade 2 aren't able to get passive boosts just from being played on Switch 2 that'll be disappointing.
With the way backwards compatiblity works with game consoles, probably not.
Same reason why most PS4 games don't get any passive upgrades from being played on PS5 (looking at you Bloodborne). Only games that were explicity patched to take advatage of the extra hardware on the PS4 Pro/PS5/PS5Pro get improvements.
Only things I've ever seen getting passive improvements are loadtimes are occasionally accidental slowdowns.
many switch games use dynamic resolution so the graphics get downgraded in certain areas
with the switch 2, games should technically be able to run at their max resolution all the time
If the game is coded to lower the resolution under certain in game conditions (number of ojects or lightning conditions for example) it doesn't matter how much hardware power the switch has, it'll lower the resolution. Only thing that can fix that is a software patch.