Book time

This book is my ideas but I own none of the characters in this story and it's my ideas though please do not take any of my ideas
Voldemor defeated dumbledore before Harry Potter even knew about wizards since then voldemor became king and any first year students who where going to start the first year as 18 rather than 11 or 12 so Harry Potter is going to be 18 for his first year yall btw if I get anything wrong please don't get mad at me I haven't read Harry Potter books in forever