Level size advice for a newb

Hi, I am building my first game with ue4 as a mobile game. It’s going to be pretty simple (of course), basically a random maze to move through.

The advice I am looking for is on level size for the maze, what sort of limits should I place on these so that it’s not overloading the android phones, is it a physical limit like X many units square, or more of a memory limit?

I don’t expect this to be used on every phone ever made, just a sort of average phone (whatever that is these last few years)