I dont understand the syntax of RigidbodyConstraints2D and freezeposition, I keep getting an error C#

My problem is only in the last collision function. Neither that line nor the line commented out work. The error is that I need to qualify it with a name, but isn't that what I'm doing when I say "GameObject.Find("Player01")? Thanks in advance, this shouldn't be a big problem but I've been totally stuck on it.

using UnityEngine; using System.Collections;

 public class Player : MonoBehaviour {
 public float speed = 1f;
 public float jumpSpeed;
 public Rigidbody2D rb;
 
 void Start () {
     rb = GetComponent<Rigidbody2D>();
 }
 
 void Update () {
     if (Input.GetKey (KeyCode.D) && (transform.position.x < 3.5)) {
         transform.position += new Vector3 (speed * Time.deltaTime, 0.0f, 0f);
         transform.localScale = new Vector3 (2.25f, 2.25f, 0f);
     }
     
     if (Input.GetKey (KeyCode.A) && (transform.position.x > -3.5)) {
         transform.position -= new Vector3 (speed * Time.deltaTime, 0.0f, 0f);
         transform.localScale = new Vector3 (-2.25f, 2.25f, 0f);
     }
     
     if (Input.GetKeyDown (KeyCode.S)) {
         gameObject.GetComponent<Rigidbody2D> ().gravityScale += 1;
     }
     
     if (Input.GetKeyDown (KeyCode.W)) {
         gameObject.GetComponent<Rigidbody2D> ().gravityScale -= 1;
     }

     if (Input.GetKeyDown (KeyCode.Space)) {
         rb.AddForce(transform.up * jumpSpeed);
     }
 }

 void OnCollisionEnter2D(Collision2D col) {
     if (col.gameObject.name == "Platform01") {
         gameObject.GetComponent<RigidbodyConstraints2D>().FreezePosition = true;
         //GameObject.Find("Player01").GetComponent<RigidbodyConstraints2D>().FreezePosition = true;
     }
 }

}