Make point cloud an object and intersect with cube

Hi everyone,
I’m new in Unity and I have to work on an university project.
I have a point cloud whose shape is an 3d rectangle. I would like to intersect it with another 3d box. I want to highlight the part of the 3d box which does not intersect the cluod point.
How could I do?
There is a C# method for a script that provides the boolean function of subtraction?
Any suggestion is welcome.
Thank you all