Unity Colour per Instance.

ColorSetter.cs

[RequireComponent(typeof(Renderer))]
public class ColorSetter : MonoBehaviour
{
    private const string PROPERTY_ID = "Target Color";
    private Renderer _renderer;

    private void Start()
    {
        _renderer = GetComponent<Renderer>();
    }

    public void SetColor(Color color)
    {
        var materialPropertyBlock = new MaterialPropertyBlock();
        materialPropertyBlock.SetColor(PROPERTY_ID, color);
        _renderer.SetPropertyBlock(materialPropertyBlock);
    }
}