Sony FX 6 Quick Start Manual page 130

Cine EI: Using other LUTs
If you apply other built-in LUTs or custom LUTs, they will have different brightness
levels and will have to exposed differently than the built-in s709 LUT.
Once a LUT is applied, you should be able to judge exposure by eye but if you want
to be more accurate, look for any documentation that comes with the LUT.
Different LUTS will also have different white balance levels.
White balance once the LUT is turned ON in the camera menu.
Another FX6 built-in LUT is the 709 800 LUT.
For the 709 800 LUT: expose a white card at 90 %, gray card at 45 %.
This LUT makes the image look brighter and more contrasty.
In all cases, the video file is recorded as a neutral Slog 3 image. You are not forced
to apply the same LUT in postproduction. You can use another LUT or grade from
scratch.