Does Redmi Watch 4 support device password (off-wrist password) function?

Yes. After this feature is turned on, the watch will activate the password lock screen when it detects that it is not being worn. To ensure information security, the password is a 6-digit number in the combination of 0-9.
Enabling method:
Watch side: Go to [Settings] >> [Device Password] >> enable [Password] >> set input password.
App side: Go to the [Mi Fitness] App >> [Device] >> [Device Password] >> [Unlock Password] >> set password.