Canon EOS R5 Advanced User's Manual page 167

Note
The Speedlite will automatically fire an AF-assist beam as needed, if autofocusing
is difficult under low light.
You can also set flash exposure compensation on the Quick Control screen ( ) or
in the [Flash function settings] setting of [ : External Speedlite control] ( ).
The camera can turn on certain Speedlites automatically when the camera is
turned on. For details, refer to the instruction manual of Speedlites that support this
feature.
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