Darnold attended San Clemente High School in San Clemente, California. After playing baseball in his freshman year, he played football and basketball.
On the football team, Darnold played wide receiver and linebacker, though he played quarterback as a sophomore after the starting quarterback was injured in a game against Tesoro High School. He threw a touchdown pass and scored the game-winning two-point conversion, but returned to playing receiver and linebacker a week later. When he legitimately became the school's quarterback, Darnold broke the school record for the most touchdown passes in a game when he threw five on two occasions.
He ended his senior season with 3,000 passing yards and 39 touchdowns, along with 800 rushing yards and 13 rushing touchdowns.
However, here is a very amusing clip of him saying he wasn't even aware of what a scholarship was before he received one from the University of Utah...
https://www.youtube.com/shorts/gqZim4QF0tI