Player(Cube) shrinks on KeyCode.F and back to original scale

I am fairly new to programming and learning on my own and I’m trying to shrink a cube on KeyCode.F, my objective is to press F and shrink the cube and press F again to resize back into its original shape i have gotten progress and figured out how to shrink it but I’m confused on how to resize it. Help would be appreciated here is my code

Placed in Update

public Vector3 localScale;

if (Input.GetKeyDown (KeyCode.F)) {
gameObject.transform.localScale -= new Vector3 (0.1f, 0.3f, 0.1f);
}

Try This
Option :1

void Update()
{

		if (Input.GetKeyDown (KeyCode.F)) 
		{
			if(gameObject.transform.localScale.x==1)
			gameObject.transform.localScale -= new Vector3 (0.1f, 0.3f, 0.1f); 
			else 
				gameObject.transform.localScale = new Vector3 (1f, 1f, 1f); 
			
		}

     }

Option 2:

bool shrink=false;
	void Update() 
	{

		if (Input.GetKeyDown (KeyCode.F)) 
		{
			if (!shrink) 
			{
				gameObject.transform.localScale -= new Vector3 (0.1f, 0.3f, 0.1f); 
				shrink = true;
			} 
			else 
			{
				gameObject.transform.localScale = new Vector3 (1f, 1f, 1f); 
				shrink = false;
			}
			
		}

     }

Second option worked for me thank you