Canon EOS R5 C User Manual page 709

Retract lens on power off
You can set whether to retract gear-type STM lenses (such as EF40mm f/2.8 STM)
automatically when the camera's power switch is set to <
ON: Enable
OFF: Disable
Caution
With auto power off, the lens will not retract regardless of the setting.
Before detaching the lens, make sure that it is retracted.
Note
When [Enable] is set, this function takes effect regardless of the lens's focus mode
switch setting (AF or MF).
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