Unless you got AppleCare with theft coverage then the AppleCare part of this is moot. File a claim if you have AppleCare+ with Theft and Loss coverage. Read this support article for more information --> File a claim if you have AppleCare+ with Theft and Loss coverage - Apple Support
Meanwhile, read this support article about what to do if a iPhone or iPad is lost or stolen -->
Find your lost iPhone or iPad - Apple Support
- The Find My service described in the article is the only recovery feature Apple offers. It must be set up before the device is lost.
- Note that if you remotely erase your device as instructed in this article, if you subsequently remove it from your account as in this article --> Check your Apple Account device list to find where you’re signed in - Apple Support , then according to this article --> How to remove Activation Lock - Apple Support you remove activation lock from the device. Do not remove it from your account. If you do then a finder or thief will have an unlocked device that can be used by another person.