Hi shirl,
Unfortunately tools aren't going to help you with an iCloud lock. That's a function of the Apple servers the phone connects to in order to provide service and only Apple can remove it. In other words, it's a software lock, not a hardware one and all the tools in the world won't let you remove it.
Your best bet is to contact the person whose account the phone is locked to and ask them to remove the phone from their iCloud account. Otherwise, with all the security features Apple has put in place on the iPhone 12, that phone is going to be pretty much useless.
If it's your own account and you've lost the login information, you can take the phone to Apple and they'll remove the iCloud lock but you have to have the original proof of ownership.
If you bought the phone from someone who sold it as being able to be activated, then you need to return it and get your money back.
Sorry I don't have better news for you, but that's just the way it is with Apple products.