You can constrain aspect ratio to 0.5625 in your camera settings and this seems to work fine for some projects.
In my case doing the above would stop all my paper2D sprites from moving so I had to us the option above for desktop and for mobile I did the following:
Leave constrain aspect ratio “off” in your camera settings and in project settings go to Android > Maximum aspect ratio and set that to 0.5625.
Hope it helps