Need help with transforming a collider over time smoothly depending on character height

colliderTransform.cs

  public CapsuleCollider characterCollider;
	public float characterColliderStartHeight;
	public float characterColliderEndHeight;
	public float colliderTransformTime;

	private void Start() {
    		myRB = this.GetComponent<Rigidbody>() as Rigidbody;
		characterCollider = this.GetComponent("Collider") as CapsuleCollider;
		characterColliderStartHeight = characterCollider.height;
		
	}

	void Update(){
		
		isGrounded();
		
	// Jump
		if (Input.GetKeyDown(KeyCode.Space)) {
				myRB.AddForce(0,jumpHeight,0, ForceMode.Impulse);
				anim.SetTrigger("Jump");
				jumpEvent.Invoke();
		}

	}

	//public float distanceToGround;
	//public bool grounded;
	//public Vector3 hitPointInfo;

	public void isGrounded(){

		RaycastHit hit;
		Ray groundedRay = new Ray(transform.position, -Vector3.up);

		// if (Physics.Raycast(groundedRay, out hit, distanceToGround + 0.1f)) {
		if (Physics.Raycast(groundedRay, out hit, Mathf.Infinity)) { 
			
			distanceToGround = hit.distance;

			if (hit.distance > 3.0f) {
				Debug.Log("hit distance is greater than or equal to 3.0");
				//Decrease the collider size
				characterCollider.height = Mathf.Lerp(characterColliderStartHeight, characterColliderEndHeight, colliderTransformTime * Time.deltaTime);
      }
   }