Samsung Galaxy S21 ultra mobile overheating
when using video recordings or video calling or zoom on any network.
when playing call of duty battle royle on 4g lte.
when download large file on 4g lte.
look at these results if you've got the time and there are many other like these.
There's been a teardown of a few samsung note phones that show different cooling systems in multiple phones of the same model, regardless of cpu type. I would guess the same can be said for any current Galaxy phone on the market. That can very well be the cause of overheating issues.
I believe it will come to normal within a couple of weeks once the phone adapts to your usage. May be a couple of updates as well. Even my battery has improved drastically over time.
Hope you have a great time..
stay safe 👍🏼