Can I transfer Apple Care to my new phone?
I recently upgraded my iPhone and wanted to transfer the applecare I bought this year for my previous phone. How do I do that/can I?
iPhone 13 Pro Max
You cannot transfer a plan from one phone to another. You cancel the plan on the previous phone and if you paid in advance for the plan, Apple will give you a prorated refund of the portion of the plan you didn't use. Then you purchase a plan for your new phone.
See this to cancel the plan on your previous phone --> Cancel or change the payment method for your AppleCare plan - Apple Support