iPhone xsMax volume going crazy.

It all started with the volume up button not working. I noticed it first when using it to take take screen shot (in concert with the power side button) my phone kept shutting off. In order to raise the volume I had to enable additive touch and designate 3D press for volume up. Now the volume has been going up to max with out input. Hopefully, unlike the other responses people have receive here like , “Hi so&so” which seems more like a chat to know ya instead of solving a problem. So whomever (apple expert) please don’t reply with, Hi Diaster, just simply provide input on solving the problem. Many others are reading this post seeking the same answer! Thank you!