my screen touches things on its own

All day my iPhone Xs Max was working fine and then all of a sudden I couldn’t touch the screen much without it glitching out and touching random spots opening apps, typing random letters etc. it’s almost like there’s water on the screen but there is no water. I can’t even turn off the phone because that involves me sliding the power button to the side. I’ve updated to the latest software and that still hasn’t fixed the issue.

at first I thought it was a low battery issue so I charged up to 50% and it still does that.

any suggestions on what to do?