‘Syncing” iPad and iPhone
My wife gets notice when receiving calls and messages on her iPad and iPhone How do I link my iPhone and iPad to do that?
iPad Pro, iPadOS 14
Your iPhone and iPad need to be signed in with the same Apple ID..
On both the iPhone and iPad, you should go to Settings > Messages and make sure iMessage is turned on
On the iPhone go to Settings > Messages > Text Message Forwarding and there should be a switch for you iPad, turn that on
iPhone Text Message Forwarding - Apple Support
On the iPhone go to Settings > Phone > Call on Other Devices and turn on the switch for your iPad
Allow phone calls on your iPad, iPod touch, and Mac - Apple Support