Canon EOS 250D Advanced User's Manual page 194

Grid when shooting
z
With [3x3 l] or [6x4 m], you can display grid lines to help you level
the camera vertically or horizontally. Also, with [3x3+diag n], the
grid is displayed together with diagonal lines to help you compose with
better balance by aligning the intersections over the subject.
Selecting [z: Dust Delete Data] or either [Clean manually] or [Clean
z
nowf] under [5: Sensor cleaning] will stop the Live View shooting. To
start Live View shooting again, press the <A> button.
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