I also upgraded to S20 from S9 and I jus literally got my new phone today, after transferring my files (I dont play games, I dont have many apps installed too, just fb,messenger, email and some photo apps) after doing so, I was just browsing/scanning thru my fb and I noticed that my phone was overheating (not just warm but overheating)
I upgraded because I had the same issue with S9 after 1 yr of using it
The phone may have still been indexing after the the transfer of files and setting itself up to learn your usage habits @IrishD
Typically there is more warmth as a person uses the phone a little bit more to check out new features and tweaks settings etc.
If this does continue however I would suggest to use a Samsung Experience Store or Samsung Service Centre for a diagnostic and or have it swapped out due to the length of time the phone has been owned. Check out any relevant Cooling Off Period.
I wish you all the best with this situation.
🌈 Stay Safe 🌈
Current Phone ~
Samsung Note 20 Ultra 5G SM-N9860_256Gb SnapDragon 865+
Samsung One Ui 3.1/ Android 11.
Yes. I identfy with your situation. A couple of days after a got my S20 Note, I was doing normal tasks and I felt my phone heating up like I was about to cook a steak! At that time, I received a call and when I put the phone to my ear. I felt I was being branded. I'm waiting for a phone call from customer service about the speaker level when taping videos today, a separate issue . My Note 10+ was a beast, I expected the S20 NOTE to be BETTER, but in limited review, it isn't! Now, I'm still in my buyer remorse phase, so, I'll see how it works for a week, Stay safe to stay alive!