Had the same thing happen to me today on my 10 month old iPhone XS Max, midway through the day my screen randomly started tapping things and zooming in, and even ended up disabling itself from putting in the password wrong. I let the device die and charged it back up to no avail, I downloaded latest version of iOS 14 a few days ago, I am taking it in to my local apple service center tomorrow, touch is unresponsive other than whatever it's doing to itself