I want to transfer my AppleCare to my new iPad, how can I do this

You cannot transfer an AppleCare+ plan between devices - but you can cancel an existing AppleCare+ plan and receive a pro-rata refund for the unused period of cover:

https://macreports.com/how-to-cancel-your-applecare-plan-and-get-a-refund/

Should you choose to add an optional AppleCare+ to your new iPad, you must do so within 60-days of purchase:

Buy an AppleCare plan - Apple Support