How can I unlock my iPhone 12pro without it getting blocked

Your phone is already blocked in that you can't get in if you have forgotten your passcode. And the ONLY way around that is to use a computer to erase the phone and set it up again. Assuming you've routinely backed up your iPhone, you'll be able to restore you backup to the phone once back in. If you haven't been backing up your iPhone, your data will be gone and you will need to start all over again. Backups HAVE to occur before something goes wrong.

Here is a link with directions on how to use your computer to restore your iPhone --> If you forgot your iPhone passcode, use your Mac or PC to reset it - Apple Support

The only way to do that is to remember your passcode.

What do you mean “blocked” ?

You shouldn’t have any problem resetting your phone.