Why is Face ID missing on my new iPad Air?

All models of iPad in recent years support either TouchID or FaceID - but not both.

All iPad models that support TouchID have a physical Home Button at bottom centre of the screen - within which is the TouchID sensor - or incorporate the TouchID sensor within the Top (Sleep/Wake) button. Only iPad Pro models support FaceID.

iPad models supporting FaceID, such as your iPad Pro, have a FaceID sensor (consisting of an Infrared Dot Projector and TrueDepth Camera array) - this sensor being absent from iPad models that support TouchID.

If FaceID isn't working as expected, or has been disabled, you’ll need to follow this guidance:

If Face ID isn't working on your iPhone or iPad Pro - Apple Support

If an alert says Face ID has been disabled on your iPhone or iPad Pro - Apple Support

If you unable to resolve a problem, you would be well advised to seek assistance directly from Apple Support:

Official Apple Support

You might also visit the Genius Bar at your local Apple Store or Apple Authorised Service Provider (AASP) - where the technicians will be able to test and assess your device. If a fault is confirmed, you'll be in the best possible place to explore your available options:

Genius Bar Reservation and Apple Support Options - Apple

Apple does show the respective sensors in their product descriptions, but they don't necessarily highlight which features one model doesn't have unless you go to the product comparison pages.

iPad Pro uses faceID

Ipad Air uses fingerprint

You can’t use faceid on the iPad Air because it doesn’t have the hardware required for faceID.

You can’t use touchid on the pro because it doesn’t have the hardware to do it.