Unity 2D Sprite Fade In/Out OnTriggerEnter2D

Hello!

First I'd like to establish I'm very VERY new to coding. This being said, I'm currently messing around with the 2D engine, and what I want to happen is have the player enter a trigger volume and when they do a sprite fades to a completely transparent alpha, and then when they exit the trigger volume it goes back to a 100% alpha.

I've found some codes that I was able to somewhat modify to the task, however in one way or another they don't exactly meet what I want. I've been trying to modify a particular code to no avail, however in its untouched state it does exactly what I want except on a clock instead of when they player enters/exits a trigger.

When I change it to OnTriggerEnter2D instead of start function, it triggers the clock. Then I tried making a boolean variable that would make it so the coroutine would run only once, however that didn't work and it looped no matter what I tried. Then I tried getting rid of the coroutine and just making the OnTriggerEnter function run the code, however because it's using yield return I have to have it in an IEnumerator which I'm not sure how to trigger with a function. I've also tried looking into using the actual SpriteRenderer component, however from my research searching through UnityAnswers they said it's apparently unstable to change it with that.

What would you recommend I do? Here's the original code I've been trying to modify, courtesy of another Unity Answers post.

 using UnityEngine;
  using System.Collections;
  
  public class Fade : MonoBehaviour
  {
      public SpriteRenderer sprite;
  
      public Color spriteColor = Color.white;
      public float fadeInTime = 1.5f;
      public float fadeOutTime = 3f;
      public float delayToFadeOut = 5f;
      public float delayToFadeIn = 5f;
  
      void Start()
      {
          StartCoroutine("FadeCycle");
      }
  
      IEnumerator FadeCycle()
      {
          float fade = 0f;
          float startTime;
          while(true)
          {
             startTime = Time.time;
             while(fade < 1f)
             {
                 fade = Mathf.Lerp(0f, 1f, (Time.time - startTime) / fadeInTime);
                 spriteColor.a = fade;
                 sprite.color = spriteColor;
                 yield return null;
                 print ("Step 1");
             }
              //Make sure it's set to exactly 1f
              fade = 1f;
              spriteColor.a = fade;
              sprite.color = spriteColor;
              yield return new WaitForSeconds(delayToFadeOut);
             print ("Step 2");
  
              startTime = Time.time;
              while(fade > 0f)
              {
                  fade = Mathf.Lerp(1f, 0f, (Time.time - startTime) / fadeOutTime);
                  spriteColor.a = fade;
                  sprite.color = spriteColor;
                  yield return null;
                 print ("Step 3");
              }
              fade = 0f;
              spriteColor.a = fade;
              sprite.color = spriteColor;
              yield return new WaitForSeconds(delayToFadeIn);
             print ("Step 4");
          }
      }
  }