How to check if a collider is overlapping with a layer?

I'm trying to make a VVVVVV copy as my first game, and I need the code to check if one of the two colliders right above and below the player (which I call feet) are overlapping with the ground layer, but I don't know how to make the code do that. This is the code I wrote so far:

 using UnityEngine;
 
 public class Movement : MonoBehaviour
 {
 
     public bool grounded;
 
     public Rigidbody2D rb;
 
     public GameObject playerFeetU;
     public GameObject playerFeetD;
 
     public LayerMask wall;
 
     void Update()
     {
 
         if (something i dont know)
         {
             grounded = true;
         }
 
         if (Input.GetKey("up"))
         {
             if (grounded == true)
             {
                 rb.gravityScale = -rb.gravityScale;
                 //Flips gravity
             }
         }
     }
 }

Thanks!