Police-panic mode for Apple Watch?
On your iPhone in the Apple Watch app, scroll down to Passcode.  Create a Passcode then enable “Turn Passcode On”.  Scroll down and enable Wrist Detection. With that enabled, anytime your Apple Watch is not on your wrist, passcode needs to be entered to access any of the watch functions.
However, if they are hell-bent on accessing your watch information, while you are wearing the watch… nothing is stopping them from cutting your arm off and using your watch while it’s still on your wrist LOL