Hi, you had a problem at my watch enlarges the screen
First try to long press the side button until the watch reboots. Hopefully that will clear the cache and then see how it behaves.
this isn’t a problem, it comes from a app that u probably have installed, like in my case it came with (assistive touch) it’s one of the options which is triple tap to enlarge the screen, triple tap to go back to normal mode… more like a zoom in and out as you can’t move around while it is zoomed in. Me personally I like it, sometimes is useful… if you are not happy with it clear you cache as Pablo said after uninstalling the app that a are causing it, hope it helps! 
You can use settings search from the market as well. Look for accessibility options and turn of the tap to zoom function - if it’s on…