https://techcrunch.com/2018/09/19/ios-12-1-beta-hints-at-new-ipad-pro/

iOS 12 is still brand new, but Apple is already testing iOS 12.1 with a developer beta version. Steve Troughton-Smith and Guilherme Rambo found references to a brand new iPad that would support Face ID.

First, there are changes to Face ID. You can find references to landscape orientation in the iOS 12.1 beta. Face ID on the iPhone is limited to portrait orientation. Chances are you didn’t even notice this limitation because there’s only one orientation for the lock screen and home screen.