Canon EOS R6 Mark II Mirrorless Camera with 24-105mm f/4-7.1 Lens - Manual (Page 554)

Adjusting the Zone AF Frame Size
You can resize the Zone AF frame displayed for Flexible Zone AF 1–3.
1.
Press the < > button during shooting screen display.
2.
Press the < > button repeatedly, select Flexible Zone AF 1, 2, or
3, then press the < > button.
3.
Adjust the Zone AF frame size.
Use the < > or < > dial to adjust the Zone AF frame size, then
press the < > button.
To restore the default setting, press the < > button.
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