Games that ran at 1080p in docked mode should be able to do that on Switch 2, presumably the console could be smart enough to run the game at that resolution even in portable mode.
Otherwise, that definitely depends on the game engine and game programming. Not every game can handle arbitrary resolution changes.
Do the switch 1 titles run in native (e.g. not upscaling) 1080p without paying more since that should just be a simple render change?
Games that ran at 1080p in docked mode should be able to do that on Switch 2, presumably the console could be smart enough to run the game at that resolution even in portable mode.
Otherwise, that definitely depends on the game engine and game programming. Not every game can handle arbitrary resolution changes.
Some games will be getting free updates for that, yes.