Lagway attended Willis High School in Willis, Texas.[1][2] As a junior in 2022, he passed for 2,081 yards with 24 touchdowns and five interceptions.[3] Prior to his senior season in 2023, Lagway participated in the Elite 11.[4] As a senior, he passed for 4,631 yards with a Texas Class 6A record 58 touchdown passes, and added 975 rushing yards with 15 touchdowns.[5][6] He was named the MaxPreps National Player of the Year[7] and Mr. Texas Football.[8] For his career, Lagway had 8,392 passing yards and 100 passing touchdowns with 2,196 rushing yards and 29 rushing touchdowns.[9]