Launch Screen File with different images

My design team has given me various launch screen images for all types of screen sizes found here.

I want to support iPhone 6+ and iPad Pro so I know launch screen files should be used instead of image assets.

However, how do I specify in my launch screen file the different images for each screen size? I thought size-classes would be the way to go but I can't differentiate between iPad Air 2 and iPad Pro that way.

There's also no iPad Pro image asset either.