Change screen time password to 10 digit alphanumeric

I'm trying to prevent myself from overusing my iPhone and it seems like this is exactly what the screen time app was designed for but to my surprise it is utterly useless. It requires only a 4 digit password to unlock. What I was hoping to do was to write down a long 16 digit password that I can't remember on a piece of paper then store the paper in an inconvenient location that is very hard to reach. But I can't do that since it only allows for a 4 digit number. But I can't forget a 4 digit number so I have no way of making a sufficiently strong password. I'm aware that you can change the password to your device but that is easily worked around since one need only ask to change the password through email. This is an incredible oversight and I can't believe Apple would be so shortsighted as to botch this but I really see no way to create a sufficiently strong password using screen time. I also have no friends and am completely alone in the world so I can't ask someone else to make the password but even if I did have such a person that is not a solution since I need to be able to access the password in certain emergencies. I just want to make unlimited access to the iPhone hard to obtain not impossible.