That… is pretty much impossible. Genshin Impact never even came close to running actually smooth 120 FPS on M1 iPads - or to be more accurate, not for any appreciable length of time.
For that matter, even a smooth 60 FPS is 100% impossible under sustained load on any setting other than Low resolution (with all else High). There have been many complaints about it for months now on social media and nothing has changed.
It has horrible sustained performance - it’s possible to “showcase” the game running on High 60 for 15-20 minutes in slow overworld fights, but as soon as the temperature goes up sufficiently it absolutely kills performance and only provides smooth 60 on Low (which looks blurry and pretty bad).
It’s even very easy to purposely throttle it, all you have to do is go repeatedly fighting ruin machines by following Mihoyo’s interactive map for spawn points, or fighting Lawachurls one after another the same way. Or 10-15 dungeon runs, demanding areas like Serai and Dragonspine blizzard etc. You can even get it to lag by using particular characters and effects - Kazuha’s burst, Ganyu’s charge shots repeatedly, pyronado, combined bursts, pretty much anything particle heavy and demanding bricks the iPad.
And once it starts lagging, it doesn’t stop, as you can read in countless posts both here and on Reddit etc.
I mean, it’s playable at persistent 60 on Low. But it looks blurry and pixelated.