Just found this cool trick you can do on your Samsung S21 Ultra and probably any other Samsung phone.
If you have the Samsung Members App installed, at the bottom of your screen click on 'GET HELP' and then go 'Phone Care' and "Interactive Checks' and you can test 12 different hardware components of your phone.
See attached images.
Ignore the exclamation mark on my camera as I abandoned the camera chec, will get to it later.
Did you also know that, if you click on your device name (SM-G998B in the 1st pic), you can check for OTA updates there? if you haven't already done so, run AUTOMATIC CHECKS to find out how you can further optimise your device.