If you want to do it this way, you’ll need an array floats which represents the scale of each actor. Each float occupies the same index as the actors do in you main array.
You can use a lerp to go from the current size, to the target size.
It’s still going to run like a dog with a wooden leg though.
What would work a lot better, is to do this in the material using world position offset. The material instance is set to adjust the ‘fade point’ depending on distance from the origin ( or a fixed point ).
Much faster.
PS: Tell me if you need help with that.