How can i reverse a function by doing the same action again?,How do I revert a transformation after previously transforming it?

So, i'm very new to coding in c#, and i'm mainly just testing things out. At the moment, I have an option to where whenever you click on the square, it shrinks by a factor of 2 and changes colour. I would like to implement this for different puzzles and would like to revert the changes back to its original transformation if I click it again. Here's the function:

private void OnMouseDown()

 {
     //shrinks the square by a factor of 2
     tr = GetComponent<Transform>();
     transform.localScale = new Vector3(0.5f, 0.5f, 0.5f);

     //changes colour to blue
     rend = GetComponent<SpriteRenderer>();
     rend.color = Color.blue;

     //changes hitbox to a suitable hitbox for the square
     hb = GetComponent<BoxCollider2D>();
     hb.size = new Vector2(1f, 0.94f);
 }

Pretty much I thought this would be useful for climbing through smaller areas and then it would be necessary to go back to normal in some other areas. any help is appreciated thanks.