How to manage Screen Time after turning 18 and leaving a Family Sharing?

So I turn 18 tomorrow and was wondering what’s going to happen to my screen time? My parents have had control over it even though I pay for my phone, phone line, and the extras. I keep seeing people saying “just change your Apple ID password to get in” but if I do then my dad will throw a fit. I just need help understanding it it will just go away once I leave the family sharing group or what.

[Re-Titled by Moderator]