iPhone 12 Pro Max unusable after ioS18 update

I recently updated my iphone because it was having some minor glitches but after updating it has become unusable. It will click and open things on its own and will never press the buttons I want to press. I somehow factory reset it but there are some parts of the screen that just wont type, I cant login to my account because the keyboard wont press 'a'. It also keeps crashing every 2 mins so much so it wont let me set it up with my Ipad without crashing halfway. Any advice?