In January 2018 Loos competed at the RD761 International Junior Team Cup where he helped USA finish third in the team competition. Individually he finished seventh in the all-around and won silver on floor exercise and bronze on vault.[3] In August Loos competed at the U.S. National Championships in the junior 17-18 division. He placed second in the all-around behind Brandon Briones.[4] Loos was selected to represent the United States at the Pan American Championships alongside Cameron Bock, Spencer Goodell, Kanji Oyama, and Genki Suzuki.[5] Loos helped the United States win gold as a team.[6]
2019
Loos competed at the 2019 Winter Cup where he placed 16th in the all-around but won bronze on floor exercise behind Sam Mikulak and Jacob Moore.[7] In August Loos competed at the U.S. National Championships where he finished 10th in the all-around and fourth on floor exercise.[8]
2020–21
In early 2020 Loos competed at the Winter Cup and finished 18th in the all-around.[9] He also started competing for the Stanford Cardinal in collegiate gymnastics; however the NCAA season was cut short due to the ongoing COVID-19 pandemic.[10]
Loos returned to competition at the 2021 Winter Cup where he finished second in the all-around behind Cameron Bock.[11] He next competed at the 2021 NCAA Championships where he helped Stanford defend their team title. Individually he won bronze on rings.[12]
Loos was selected to compete at the 2021 Pan American Championships; he helped the team win the silver medal behind Brazil and individually he finished fourth in the all-around. Due to competing at the Pan American Championships, Loos was invited to compete at the upcoming Olympic Trials.[13]
Loos finished ninth in the all-around at the Olympic Trials and was not added to the team.[14][15] In September Loos was selected to compete at the Koper Challenge Cup.[16] While there he finished fourth on floor exercise and rings and eighth on vault.[17]
In June Loos was selected to represent the United States at the Pan American Championships alongside Brody Malone, Yul Moldauer, Colt Walker, and Shane Wiskus.[22] On the first day of competition Loos competed on floor exercise, rings, vault, and horizontal bar to help qualify the United States in first place to the team final. Individually he won silver on floor exercise behind Moldauer and bronze on rings behind Brazilians Arthur Zanetti and Caio Souza.[23] During the team final Loos competed on floor, pommel horse, rings, vault, and horizontal bar to help the USA win gold ahead of the reigning team champion Brazil.[24]
In late July Loos competed at the U.S. Classic where he placed seventh in the all-around but recorded the third-highest vault and rings scores.[25]