The logic for doing this can be part of your Ghost’s blueprint. Putting it into the construction script or based on the Begin Play event will guarantee all of your ghosts look different.
Here is a pic!
Scale is pretty simple, I just get a reference to the static mesh for my Ghost (it was just called StaticMesh1) and set its scale to a random vector which i create from a random float in a range based on two float params in my blueprint.
The material effect requires first creating a dynamic instance of my meshes material. If you do this and don’t choose anything specific for the Source Material input then it will just use the material on the mesh at the given index. Next I make a random color using some random float in ranges.
Lemme know if anything isn’t clear!