can you unlock a iphone 12Pro if it says "Iphone unavailable"?

For an Unavailable iPhone, see the instructions in How to remove your iPhone, iPad, or iPod touch passcode without a computer - Apple Support

(Note the following from the first step:

From your device's Lock Screen, try entering your passcode until the "[Device] Unavailable" screen appears and your device asks you to try again later. When you're able to, continue trying to enter your passcode until the "Security Lockout" screen appears and you get the Erase [Device] option in the bottom corner of the screen.

If that option is not available, you will need to use a computer. See: If you forgot your iPhone passcode - Apple Support