How do i change the radius in RotateAround ?

Hello,
In my script, I have my player that move around his ennemi with RotateAround.
like this :

{
public GameObject Ennemi;
private float HorizontalMove;
private float VerticalMove;

void Start()
{
}

void Update()
{
    HorizontalMove = Input.GetAxisRaw("Horizontal");

    transform.RotateAround(Ennemi.transform.position, Vector3.up, HorizontalMove);
}

}

And i want to change the radius of the rotation so he can get closer or run away.
How can i do this ? I’m still a begginner in Unity.

My script is attach to my player.

Thank you.

Here , try this

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class PlayerRotation : MonoBehaviour {

    public Transform Enemy;
    private float _horizontalMove;
    private float _verticalMove;
    private Vector3 _playerPosition;
    [SerializeField] private float _radius;
    

    private void Update()
    {
        _playerPosition = _radius * Vector3.Normalize(  this.transform.position - Enemy.position ) + Enemy.position;       
        _horizontalMove = Input.GetAxisRaw("Horizontal");
        this.transform.position = _playerPosition;
        transform.RotateAround(Enemy.position,Vector3.up,_horizontalMove);
        
    }
}

public GameObject Enemy;
public float HorizontalSensitivity = 1;
public float VerticalSensitivity = 1;

[Range(1,100)]
public float MinDistanceFromEnemy = 1;

[Range(1,100)]
public float MaxDistanceFromEnemy = 50;

private float HorizontalMove;
private float VerticalMove;

private void Start()
{
    VerticalMove = Vector3.Distance( transform.position, Enemy.transform.position );
}

void Update()
{
    HorizontalMove = Input.GetAxisRaw( "Horizontal" ) * HorizontalSensitivity;
    VerticalMove = Mathf.Clamp( VerticalMove - Input.GetAxisRaw( "Vertical" ) * VerticalSensitivity, MinDistanceFromEnemy, MaxDistanceFromEnemy );
    transform.position = Enemy.transform.position + ( transform.position - Enemy.transform.position ).normalized * VerticalMove;
    transform.RotateAround( Enemy.transform.position, Vector3.up, HorizontalMove );
}