Accessing iPad Pro ARKit 4

Is it possible for Unreal Engine to access iPad Pro ARKit 4 data such as Depth API?

Sadly, no.
The trello roadmap says ARKit** 3.5** is done for UE4.26, no release date. Trello

There are some commits to the source code at GitHub mentioning ARKit4 beta (in the dev-vr branch),
but in general ARKit/ARCore support has always been lackluster and buggy, so even if it makes it to 4.26, careful testing required before making any plans with AR with Unreal Engine.

Thanks for the info!