McManis attended Richwoods High School in Peoria, Illinois, where he played football and was a state champion long-jumper.

As a senior, he earned first-team All-Big Ten honors after he set career highs in interceptions with five, and recorded 37 tackles, 1.5 tackles-for-loss, and broke up 12 passes.

[12] In week 5 of the 2019 season against the Oakland Raiders, McManis forced a fumble on Trevor Davis on the goal line in the 24–21 loss.

[15] During the 2020 season, McManis became the longest tenured Bears player, having played under four different coaching regimes dating back to Lovie Smith in 2012.

[16] In Week 15 against the Minnesota Vikings, McManis intercepted a pass thrown by Kirk Cousins with no time left in the game to secure a 33–27 win for the Bears.