Your phone will heat up when you play games. It's normal. You can take short breaks to allow your Motorola Edge 20's temperature to drop.
You can get rid of your Bulky Case. The Bulky Case doesn't mean your device will be safe from falls. The thicker corners make for the best cases.
The battery drains quickly when the camera is on for too long. It also heats up your phone.
If you use the flash on, the Motorola Edge 20 will heat faster and drain your battery. If it isn't necessary, switch off the flash.
streaming, editing video, WiFi Hotspot, screen mirroring and screen-mirroring.
Firmware updates can resolve most problems. If there is an update available, I recommend you to check and update your Motorola edge 20.