Neither restart nor restore worked to get the screen size back to normal. Unable to get to system preferences due to huge size of screen apps. I managed to make this mess when wiping screen to clean it.
Go to Settings - Accessibility - Zoom, and turn it off. If it's enabled, a three finger-double tap activates it. Maybe you did this by chance.
In case you can't get to Settings, perform another three finger double tap. This should reduce the size again, and you'll be able to go to Settings and disable the feature.