Apple Watch iCloud locked

Activation Lock is designed to prevent anyone else from using an Apple Watch if it's ever lost or stolen.

About Activation Lock on your Apple Watch - Apple Support

Activation Lock is an anti-theft feature that cannot be bypassed. Only the previous owner can remove the lock by using their Apple ID & password. Apple will not help you find the previous owner. If the previous owner cannot or will not remove the lock, then the watch is useless to you or anyone else. Try to get a refund (through eBay) or dispose of the watch properly. In the future, see the 'Before you buy a watch from a third-party' section in:

What to do before you sell, give away, or trade in your Apple Watch, or buy one from someone else - Apple Support

You have three choices:

1. Get the previous owner to unlock the watch, assuming you know them.
2. Get a refund if the previous owner can't or is unwilling to unlock the watch.
3. If the previous owner isn't known, can't or won't unlock the watch, nor give you a refund, recycle the watch responsibly.

Apple will NOT help you. We cannot help you. Buying used iOS/iPadOS/MacOS/WatchOS devices used is risky at best and often leads to owning a completely, totally, utterly useless device, and money lost.

Since there's a good chance you've been scammed, don't go looking for a service which claims they can unlock the watch. They can't. Even the FBI couldn't unlock the watch.

Read this --> The All Too Common SAD Reality of Buying … - Apple Community