Apple Watch with internal GPS was stolen
What should I do if my Apple Watch with internal GPS has been stolen and there’s been identity theft? Verizon won’t remove the number from my account. A franchisee employee stole the pin.
Apple Watch Series 6
See the 'Put your Apple Watch in Lost Mode' section in:
If your Apple Watch is lost or stolen - Apple Support
Also, you MAY want to see:
If you think your Apple ID has been compromised - Apple Support