Canon EOS-1D X Mark III Advanced User's Manual page 127

[ ] Color Temperature
1.
Press the <
2.
Select <
Watch the top LCD panel as you turn the <
3.
Set the value.
Turn the <
The color temperature can be set from approx. 2500K to 10000K in
100K increments.
> button ( ).
>.
> dial to set the value.
127
> dial to select < >.