Apple care expiry date

No, we cannot. This is a user to user forum, you are not addressing Apple here.

You can verify it yourself by entering the watch's serial number here: Check Your Service and Support Coverage - Apple Support

Apple Care+, if bought as a one time purchase is tied to the device, not the owner. If you sell or give your device to someone it keeps its Apple Care+.

If you are paying monthly for Apple care, instead of the one time purchase, its tied to the device and the Apple ID, and you should cancel it so it doesn't keep charging you. The new owner would not be able to get it again though.

See here: How to manage your AppleCare plan – Apple Support

You can check here;

Check Your Service and Support Coverage - Apple Support