Unreal Engine iOS Compatibility (4.25)

Fortnite DOES NOT support: iPhone 5S, 6, 6 Plus; iPad Air, Mini 2, 3; iPod Touch 6th gen and lower

Is this only about Fortnite or every ue4 4.25+ app released will also affect compatibility on those devices?
If certain rendering features prevent compatibility on those devices, how are we going to know which devices we can support?

Thank you!