How to unlock my iPhone after passcode was forgotten and now the device is unavailable

My boyfriend was trying to unlock my iPhone and entered an incorrect passcode so many times that the phone now just says that’s it’s unavailable. How can I unlock it? I don’t remember what the passcode was myself, as it is an iPhone 12 and I haven’t used it for years. I desperately want my child’s baby pictures from it and I don’t want to lose them, amongst other very sentimental pictures/videos.. Please help! Thank you