Unlike most Android issues that have steadily improved over time, overheating is just as prevalent as ever. After all, phones get more and more powerful every year, and with more power comes more heat. Sometimes, it gets to be too much, especially during years when the chips are running hotter than usual. The Snapdragon 8 Gen 1, for example, is known as just being a hot chip, so phones equipped with that processor will simply get warmer than average when under heavy use, although this is completely normal. After all, a phone has plenty of components that act as a heat sink, so it's going to get warm under heavier use. 

SlashGear has a guide on how to tell if a phone is overheating, so we'll skip the diagnostics and go to the troubleshooting. The first thing you should do is unplug your phone from any charger that it's plugged into. Charging the phone warms it up, and if you're gaming on your phone or doing something heavy, it'll get even warmer than it normally would. So, stop whatever you're doing and unplug the phone for a while to see if that cools it down. If it does, try to refrain from performing heavy activities while charging. 

Another good idea is to reboot the phone. This closes everything and starts the phone up fresh. That should cool the phone down. If none of the prior options work, go back into your trusty battery settings, see if any app is using a ton of battery life, and uninstall it. That should fix the problem. You can then reinstall the app to see if it'll play nice.