To make use of a LUT, use the following properties to assign the LUT texture to the Post Process Volume you want to use it with and adjust its intensity.
User Map -> Edit -> Post Effect option
A Lookup Table (LUT) can be used to achieve color correction using a Post Process Volume. Instead of using three one-dimensional (1D) lookup tables, a single three-dimensional (3D) Lookup Table is used. This offers more sophisticated color transformation, which can be used for something like desaturation.
Color Neutral LUT
Sepia Toned LUT