https://www.theverge.com/circuitbreaker/2018/6/5/17428462/ipad-face-id-leak-ios-12-beta

iOS developer Guilherme Rambo has been poking around the new iOS 12 beta, and code contained within appears to confirm something that has been rumored multiple times: Face ID is coming to the iPad. Videos and screenshots tweeted by Rambo show that iOS 12 contains hidden references to Face ID on the iPad, including the setup UI and relevant section of the settings menu.

It's possible that these references could pertain to a feature that lets you unlock an iPad with an iPhone X, like how you can unlock a Mac with an Apple Watch, but that seems unlikely. The inclusion of the setup UI suggests it's for a device actually equipped with the Face ID sensors, which is something that has been credibly reported as planned for this year, so it seems safe to say a iPad with Face ID is on the way.