How to make sprinting

using UnityEngine;

public class Player_Movement : MonoBehaviour
{
public CharacterController controller;

public float speed = 12f;
public float sprit = 24f;
public float gravity = -9.81f;
public float jumpHeight = 3f;

public int maxJumpCount = 2;
public int jumpsRemaining = 0;

public Transform groundCheck;
public float groundDistance = 0.4f;
public LayerMask groundMask;

Vector3 velocity;
bool isGrounded;

// Update is called once per frame
void Update()
{

    isGrounded = Physics.CheckSphere(groundCheck.position, groundDistance, groundMask);
    
    if(isGrounded && velocity.y < 0)
    {
        velocity.y = -2f;
        jumpsRemaining = maxJumpCount;
    }
    
    float x = Input.GetAxis("Horizontal");
    float z = Input.GetAxis("Vertical");

    Vector3 move = transform.right * x + transform.forward * z;

    controller.Move(move * speed * Time.deltaTime);

    if(Input.GetKeyDown(KeyCode.RightControl))
    {
        controller.Move(move *sprit * Time.deltaTime);
    }

    if((Input.GetButtonDown("Jump")) && (jumpsRemaining > 0))
    {
        velocity.y = Mathf.Sqrt(jumpHeight * -2 * gravity);
        jumpsRemaining -= 1;
    }

    velocity.y += gravity * Time.deltaTime;
    controller.Move(velocity * Time.deltaTime);

}

}

This is a fps movement script the sprinting will not work

1.Make sure you are pressing the right button… You can do this by adding a Debug statement in the script like :

if(Input.GetKeyDown(KeyCode.RightControl))
{ 
    Debug.Log("Button has been pressed")
    controller.Move(move *sprit * Time.deltaTime); 
}

Or maybe try just changing the speed variable in the script like :

if(Input.GetKeyDown(KeyCode.RightControl)) 
{
    speed = sprit; 
}
else if(Input.GetKeyUp(KeyCode.RightControl))
{
    speed = 12f;
}

Code Not Tested