How to Find TextMeshPro Objects in Hierarchy and Edit Them?

This is a bit of an oddly specific issue I'm having, but I'm making a small platformer where the platforms are all letters and such. I want the letters to change color when they're jumped on, but can't quite figure out how to get my script to find which letter I'm colliding with. Here's the code I've got so far.

 public class LetterScript : MonoBehaviour
 {

     TextMeshPro currentLetter;

     private void OnTriggerEnter2D(Collider2D collision)
     {
         if (collision.gameObject.CompareTag("Letter"))
         {
             Debug.Log("Collision detected!");
             currentLetter = (TextMeshPro)FindObjectOfType(typeof(TextMeshPro));  //I want to set currentLetter to the TMPro object I land on so that I can change its color.
             Debug.Log("currentLetter is:" + currentLetter.name);
             currentLetter.color = new Color32(255, 255, 255, 255);
         }
     }
 }