See Turn off Activation Lock https://support.apple.com/en-us/HT201441 and
About Activation Lock on your Apple Watch https://support.apple.com/en-us/HT205009. If you can't turn the activation lock off using the instructions given in the link and want to make it functional, (1) you'll need to get help from its the prior owner or (2) alternatively you'll need to contact Apple support and have your purchase receipt for the watch from an authorized Apple reseller with its serial number on it. You also will need to have a face ID. Note that being able to contact the prior owner if highly unlikely as is the prior owner will be willing to help you. The watch likely was stolen given that it is activation locked.
If you want to contact Apple support to discuss your problem, then use the support options below. Alternatively, if an Apple Store is open in your area, then you can go there to deal with your problem. In this case, you can make a genius-bar appointment (https://www.apple.com/retail/geniusbar/) if you want.
Get a call from Apple support to help solve your problem using this link https://getsupport.apple.com/?caller=kbase&PGF=PGF63005&category_id=SC0245&symptom_id=23362
Apple ID Support https://support.apple.com/apple-id
Apple Support Twitter https://twitter.com/AppleSupport
Apple ID account security for country-specific and region-specific help https://support.apple.com/en-us/HT204169
Get Support: We’re here to help https://getsupport.apple.com/. Go through the options to find the best support option.