The score gave Texas a 45-0 lead with 2:23 left in the third quarter. Earlier on the same the drive, Manning hit receiver Johntay Cook II for a 40-yard gain.
On his next drive, Manning added a 1-yard touchdown run to push the lead to 52-0.
The redshirt freshman appeared in just two games last season, making his debut in the regular-season finale against Texas Tech. Manning is part of the famous football Manning clan, as the eldest son of Cooper Manning, the grandson of Hall of Famer Archie Manning, and the nephew of Peyton and Eli Manning.
Ewers was 20-of-27 passing for 260 yards with three touchdowns and an interception before exiting.