FaceTime and iMessage from Apple Watch phone number
If I buy and set up an Apple Watch SE (with GPS and cellular) for a family member who does not have their own iPhone would they also be able to set up the newest iPad mini (with 5G) with their own Apple ID and then FaceTime and iMessage from the phone number associated with their watch while using their iPad?
I am aware that Apple Watches do not pair with iPads, I’m only concerned with them being able to FaceTime and iMessage using their phone number instead of their email address.
Thank you for your time and help.