Canon EOS R5 Mark II Advanced User's Manual page 82

4.
Look through the viewfinder.
Holding the camera horizontally, look through the viewfinder so that the
four corners of the screen appear evenly spaced.
Press the <
5.
Start calibration.
Look at the indicator displayed and press the <
Keep looking at the indicator without blinking until it disappears.
This process is repeated for indicators at five positions (center, right,
left, top, and bottom).
> button.
82
> button.