Q:

Removing launch screen file from Info.plist scales the views

I noticed something that when you remove the launch screen file entry from the XCode Info.plist file, any view of any view controller becomes scaled according to the screen size, so the views appear zoomed in on large screen sizes such as the iPad Pro (12.9 inches) and appear somehow zoomed out on smaller devices (iPad Pro 9.7 inches).
In that case it seems that the Auto Layout constraints have no effect as the scaling is done automatically.
I really can't understand what does this has to do with the layout constraints, so I appreciate if any one can explain what's the reason for that. 

A:

Without being able to provide deep details, iOS uses the launch screen definition (view or static images) to determine which size classes the app should use. If you have not supplied those, it seems you get scaling that you generally do not want. 
That doesn't mean auto-layout no longer has any affect... it just means that the auto-layout engine is not using the current screen size for its size/positioning calculations.
You'll see very similar results if you explicitly set your project for iPhone only.
Simple, obvious solution: Don't remove the launch screen.

