How to change variable in material per instance in instanced static mesh?

How can i change a variable per instance in a dynamic material instance/normal material, inside an instanced static mesh?

You cannot change the material of a specific instance of an instanced static mesh component. All instances share the same material and mesh, this is why instanced static meshes are so performant.

So, replace the instance with a non instanced version. Still get the performance benefit, but that one instance is now individualized and managed completely different.

If you Need to do this fore more than 1 instance, you may want to consider running multiple instances of the new type of mesh concurrently.
Make a blueprint with multiple hism components that can allow you to manage it in different ways.

Hello, you can use Custom Primitive data as explained here:

Or with the more recent UI: