Canon EOS 90D Advanced User's Manual page 136

Selecting the AF Method (Live View Shooting)
Prioritizes focusing on the nearest subject. Faces of any people in the Zone
AF frame are also given priority in focusing.
AF points in focus are displayed with < S >.
136
: Zone AF
Uses auto selection AF in Zone AF frames
to cover a large area, which makes
focusing easier than with 1-point AF.