most of high graphics games or large app cause this problem if you watching them for long time..anyway do this steps...turn off wifi,internet, bluetooth, if it's not in use,,put battery into auto optimization mode..try to put sleep mood for unused app...put phone into safe mood to see any apps creating a issue or not,,,,,try to set black theme or wallpaper,,put brightness less than 50%
Bro, if it's really hot to use, then contact service center..because till now I never faced any heating issue in my device(S10+) . Meanwhile try to find out, what causing this issue and from when its happening like while charging, using camera, playing games, watching videos or any other activities causing it. If its happening after update or after installing any 3rd party apps, then try to keep a tab on such apps.. (you can check for such apps by using your phone in safe mode) Or keep all apps to immediate sleep mode when not in use, change your display resolution from wqhd+ to fhd+, restrict apps background usage, reduce brightness .. or try one more thing go to settings-select applications-click at 3 dots and select reset app prefrences
