Canon EOS-1D X Mark III Advanced User's Manual page 387

AF point brightness
AF point brightness in the viewfinder is adjustable.
AF status in viewfinder
You can select whether to show the AF status indicator inside or outside of the viewfinder's
field of view.
[ ] Show in field of view
< > is displayed in the lower right within the viewfinder's field of view.
[ ] Show outside view
< > is displayed below the focus indicator <
view.
Note
For AF status indicator details, see
AF Microadjustment
You can make fine adjustments for the AF's point of focus. For details, see
Microadjustment.
>, outside the viewfinder's field of
AF Status Indicator (Viewfinder
387
Shooting).
AF