Unity 2D Platformer: How to properly implement this ground check?

So I've been tinkering away with a 2D player controller and have slowly been making progress. One challenge I've run into is the ground check. The code below is what I have so far. I've removed the other bits of code for movement and jumping just to focus on the ground check.

 [Header("Ground Check")]
 [SerializeField] bool isGrounded; // Serialized for testing in editor
 [SerializeField] LayerMask whatIsGround;
 [SerializeField] float groundCheckRaycastDistance;

 void Update()
 {
     GroundCheck();
 }

 private void GroundCheck()
 {        
     isGrounded = Physics2D.Raycast(transform.position, Vector2.down, groundCheckRaycastDistance, whatIsGround) ||
                  Physics2D.Raycast(new Vector2(transform.position.x - 0.5f, transform.position.y), Vector2.down, groundCheckRaycastDistance, whatIsGround) ||
                  Physics2D.Raycast(new Vector2(transform.position.x + 0.5f, transform.position.y), Vector2.down, groundCheckRaycastDistance, whatIsGround);


     // Draws the raycasts for use in testing
     Debug.DrawRay(transform.position, Vector2.down, Color.white);
     Debug.DrawRay(new Vector2(transform.position.x - 0.5f, transform.position.y), Vector2.down, Color.white);
     Debug.DrawRay(new Vector2(transform.position.x + 0.5f, transform.position.y), Vector2.down, Color.white);
 }

This code works perfectly but only because my player is exactly 1 unit by 1 unit in size, so the +/- 0.5 sets the raycasts exactly on the edges of the player.

Is there a way to do this so the raycasts come exactly from the edge of the player without just putting in numbers? Something to do with bounds maybe?