Celia graduated from Knoch High School in 2018 where she was a four year varsity starter. She was named All-Section during her junior and senior seasons as a pitcher.
Celia went on to Saint Vincent College and as a freshman she was named Presidents Athletic Conference Player of the Year, PAC Tournament Most Outstanding Player, PAC All-Tournament Team and All-PAC First Team. Knappenberger ended the year with a record of 16-9, throwing 168.1 innings with an ERA of 2.30. She ranked first in the PAC in wins, ERA, and complete games while being second in the conference in innings pitched, strikeouts and tied for first in saves.
Due to the COVID-19 pandemic, the next season was abruptly cut short, leading to unfortunate circumstances for Celia as she experienced a career-ending injury that deprived her of her senior year. However, she now aspires to impart the valuable lessons she has learned to younger girls and pass on her passion for the game to them.