Canon EOS R6 Mark II Mirrorless Camera with 24-105mm f/4-7.1 Lens - Manual (Page 510)

Setting MF Peaking (Outline Emphasis)
Edges of subjects in focus can be displayed in color to make focusing easier. You can set
the outline color and adjust the sensitivity (level) of edge detection.
1.
Select [ : MF peaking settings].
2.
Select [Peaking].
3.
Select [On].
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