Where should these functions be?

I am trying to make a skill system a bit dynamic. Currently I have a class named Skill that looks something like this.

 public class Skill: MonoBehaviour
 {
     //fields
     //properties
     //start
     //core functions
 }

However, there are some functionalities that can be used to “tweak” the skill sometimes.

For example, I might want to scale and change the color of some skills. I am pretty sure it justifies writing a function to handle that well instead of hard coding into every skill that might need it, but it is certainly not a core functionality.

If I put functions like this in the Skill class I feel that it will get clogged by situational things.

My current ideas are:

1 - Create a singleton SkillFunctions and throw those over there.

Let’s say there are 30 functions and every skill might end up using 1-2. Regardless of the number, there will be a reference to singleton instance anyway...so what’s the point? It get things more organized but wouldn’t that cost a lot of performance in Unity?

2 - Every functionality be a class, then I could AddComponent to the Skill gameObject whenever needed.

I don't know if I am doing something terribly wrong, but I cannot pass parameters that way as Monobehaviors should not have constructors. Example:

I could say changeColor but because every skill might want to change to a different color, having no control over the parameters would mean I could only change color to a predefined one, and not choose one on the spot...

To sum it up:

Should I have all possible things skills could do in the Skill class or is there a better way to do that in Unity?

Thank you