Ronsiek played basketball for
O'Gorman Catholic High School in
Sioux Falls, South Dakota. As a freshman, she helped her team win the Class AA state tournament, its first state title since 1995. In her senior season, Ronsiek led O'Gorman to a 21–0 record before the state tournament was canceled amid the
COVID-19 pandemic. She was named Miss Basketball and
Gatorade Player of the Year in South Dakota, and earned
Argus Leader Basketball Player and Athlete of the Year honors. Ronsiek left as the program's all-time leading scorer. She committed to playing college basketball for Creighton over offers from Colorado State, Green Bay and South Dakota. In addition to basketball, Ronsiek was an all-state
volleyball player in high school, leading the team to the Class AA state title game as a senior and breaking the program record for kills. ==College career==