player controller with extra Jump feature + flip function

Unity Player Controller

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

public class PlayerController : MonoBehaviour
{
    private int extraJump;
    public int extraJumpValue;
    public float speed;
    public float jumpForce;
    private float moveInput;
    private Rigidbody2D rigidbody2;
    private bool facingRight = true;
    public bool isGrounded;
    public Transform groundCheck;
    public float checkRadius;
    public LayerMask WhatIsGround;

    void Start()
    {
        extraJump = extraJumpValue;
        rigidbody2 = GetComponent<Rigidbody2D>();
    }


    void FixedUpdate()
    {


        isGrounded = Physics2D.OverlapCircle(groundCheck.position, checkRadius,WhatIsGround);



        moveInput = Input.GetAxis("Horizontal");
    
        rigidbody2.velocity =new Vector2(moveInput*speed,rigidbody2.velocity.y);

        if(facingRight==true&&moveInput<0)
            Flip();

        if(facingRight==false&&moveInput>0)
            Flip();

    }

    void Update()
    {

        if (isGrounded == true)
        {

            extraJump = extraJumpValue;
        }
         
        if ((Input.GetKeyDown(KeyCode.UpArrow)|| Input.GetKeyDown(KeyCode.W)|| Input.GetKeyDown(KeyCode.Space)) &&extraJump>0)
        {
            rigidbody2.velocity = Vector2.up*jumpForce;
            extraJump--;

        }else if ((Input.GetKeyDown(KeyCode.UpArrow) || Input.GetKeyDown(KeyCode.W) || Input.GetKeyDown(KeyCode.Space)) && extraJump == 0&&isGrounded==true)
        {
            rigidbody2.velocity = Vector2.up * jumpForce;

        }
    }

    void Flip()
    {
        facingRight = !facingRight;
        Vector3 scaller = transform.localScale;
        scaller.x *= -1;
        transform.localScale = scaller;
    }
}