Switch 2’s backward compability is not hardware-level, it uses a translation layer.

It’s almost complete at this point, but it’s not perfect, which is is why there are still a few games that don’t work (7 of them have been identified in the linked article).

So no, when they say they released compatibilty fixes, they didn’t tell the game to crank up the resolution, they tweaked the compatibility layer so the game run normally.

I used to have a few of the broken ones, now I think the only one still having problems is AOT2, which is on their list.