How to make light-fixtures with emissive materials that can turn on/off?

My aim is to create light fixtures that can turn on and off.

Toggling a point or spot light is easy enough but I'm using the emission aspect of a material (standard shader) for the fixture surface and I want this to dull when the light is off.

Things of note:

• This needs to work on an instance-by-instance basis.

• I'm trying to use a single material that has an albedo and emission texture on all objects in my scene.

• I'm fairly new to Unity, picking up C# pretty quickly but I'm still not fully versed on what Unity is capable of or the various methods of achieving this are available to me.

I believe I could switch the material for a different one with no emission but would this effect all instances of this prefab? Or I could switch the model out for one with different UVs.

So which way's best? Or is there another way?

Thanks.