Triggers and SendMessages. C#

I am a bit confused about the SendMessages a bit. So I created a little example mock up level to learn about it and mess with it a bit more. I am using C# to write these scripts and I am a bit lost. I have two objects. One is the player who has a flashlight attached to him (The Light holds the script to turn the light on and off) and there is a collection trigger in front of him. I made it work so if the player hits the trigger it will send a message to the light to turn it off for a given amount of time. Here are my two scripts.

Trigger.cs:

 using UnityEngine;
 using System.Collections;
 
 public class Trigger : MonoBehaviour {
     
     void OnTriggerEnter(Collider col){
         if(col.gameObject.tag == "Player"){
             gameObject.Find("Light").SendMessage("blinkingDelay", 5.0f);
         }
     }
 }

And here is the flashlight.

Flashlight.cs

 using UnityEngine;
 using System.Collections;
 
 public class Flashlight : MonoBehaviour {
     
     public bool power = true;
     
     
     // Update is called once per frame
         
     
     public IEnumerator blinkingDelay(float holdamount){
         power = false;
         yield return new WaitForSeconds(holdamount);
         power = true;
     }
 }

Now I know in order to use yield I have to call the function with: StartCoroutine. But How do I do this with SendMessage?

The error I get btw is this: "sendmessage blinkingDelay has no receiver"