Audiobus: Use your music apps together.
What is Audiobus? — Audiobus is an award-winning music app for iPhone and iPad which lets you use your other music apps together. Chain effects on your favourite synth, run the output of apps or Audio Units into an app like GarageBand or Loopy, or select a different audio interface output for each app. Route MIDI between apps — drive a synth from a MIDI sequencer, or add an arpeggiator to your MIDI keyboard — or sync with your external MIDI gear. And control your entire setup from a MIDI controller.Download on the App Store
Audiobus is the app that makes the rest of your setup better.
[Exclusive] Apple iPad Pro 12.9 (2018) Images, Specs Leaked Ahead of Company’s September 12 Launch
Full specs and info here:
In other leaks seems that Logic and Final Cut Pro X going iPad. But you seem to need at least 4GB. So only available for Pro models. Also I read on twitter that the iPhone Xs 6.5 would support iPad apps. Not clear if this is a leak, rumor or wishful thinking.