Canon EOS R5 Mark II Advanced User's Manual page 236

Registration from the menu
1.
Select [
2.
Select a custom white balance number to register the white balance
data to.
3.
Select [Record and register WB].
: Set Custom WB] (
Press < >.
Turn the < > dial or press <
[ ] (from 1 to 5), then press <
registered to the selected number.
, ).
> up or down to select a number for
>. The custom white balance will be
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