what if I forgot my screentime passcode but, it doesn't ask if "I've forgotten my passcode" how do I reset it?

If you have forgotten the Screen Time passcode and you do not see a link to reset it, the only way for you to remove that passcode is to use a computer as SravanKrA has stated and you must restore your iPhone to remove it. You cannot restore a backup, as the backup contains that passcode and you would only put it right back on the phone. You will have to set the iPhone up as new.

If you are unable to reset Screen Time passcode from the this-> link then, you will need a computer. If you don't have one, borrow from a friend.

Forgot? Click below to reset…

Click->If you forgot the passcode for your iPhone, iPad, or iPod touch, or your ...

You cannot reset the screen time passcode unless you are running iOS 13.4 or later. Your only option is to erase the phone completely and start all over again. Restoring a backup, will restore the passcode that you can’t remember.