I am looking for a code which makes sure the character is grounded when the game starts,Is there a code to make sure the character is grounded when the game starts?

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class Player$$anonymous$$ovement : $$anonymous$$onoBehaviour
 
 {
      private bool isGrounded = false;
  
      private void OnTriggerEnter(Collider other)
      {
          // Grounded
          isGrounded = true;
      }
  
      private void OnTriggerExit(Collider other)
      {
          // Ungrounded
          isGrounded = false;
      }
  }
  
     public CharacterController controller;
 
     public float speed = 12f;
     public float gravity = -9.81f;
     public float jumpHeight = 3f;
 
     public Transform groundCheck;
     public float groundDistance = 0.4f;
     public Layer$$anonymous$$ask ground$$anonymous$$ask;
 
     Vector3 velocity;
     bool isGrounded;
 
     // Update is called once per frame
     void Update()
     {
         isGrounded = Physics.CheckSphere(groundCheck.position, groundDistance, ground$$anonymous$$ask);
 
         if(isGrounded && velocity.y < 0)
         {
             velocity.y = -2f;
         }
 
         float x = Input.GetAxis("Horizontal");
         float z = Input.GetAxis("Vertical");
 
         Vector3 move = transform.right * x + transform.forward * z;
 
         controller.$$anonymous$$ove(move * speed * Time.deltaTime);
 
         if(Input.GetButtonDown("Jump") && isGrounded)
         {
             velocity.y = $$anonymous$$athf.Sqrt(jumpHeight * -2f * gravity);
         }
 
         velocity.y += gravity * Time.deltaTime;
 
         controller.$$anonymous$$ove(velocity * Time.deltaTime);
     }
 }