I have a 2016 SE model iPhone. Cannot shut it down to fix screen problem.

It's been great little phone, but last night everything on my screen suddenly went from normal size to being huge, blown up several times normal size. You can only move what's on the screen by using 3 fingers. I can't shut it down because when the slide icon comes up on the screen to finish shutting it down it's so large you can't slide it. It's a bit bizarre. Any solutions? Do I have to wipe the phone to see if that would fix it? (Time for a new iPhone it seems) Thanks!