is there a way for ipad air to use facial recognition instead of touch finger print id?

All models of iPad in recent years support either TouchID or FaceID - but not both - each being entirely reliant upon associated hardware. This cannot be added or modified.

All iPad models that support TouchID have a physical Home Button at bottom centre of the screen - within which is the TouchID sensor - or for iPad Air4 and mini6, incorporate the TouchID sensor within the Top (Sleep/Wake) button.

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.

iPhone and iPad models that support Face ID - Apple Support

Face ID can be used on iPhones and iPads in Apple's list iPhone and iPad models that support Face ID

iPad Air is not in the list.