How to find weather the function execution completed or not

Since you want to call a method if the another method gets to the end you might as well pass that method as argument.

 void CallOnCondition()
 {
     Debug.Log("Calling, other method reached the end");
 }
 
 void MainCallingMethod(Action action)
 {
     // Doing stuff here and there
     for(int i = 0; i < 10; i++ ){
         Debug.Log(i.ToString());
     }
     // I am done with my 1000 lines of smart code based on heavy and advanced algorithms
     action();
 
 }
 
 // Lets try it
 void Start(){
     MainCallingMethod(CallOnCondition)
 }

This is using delegate, notice the lack of () when passing the method. This is because we are passing the address of the method and we are not calling it. But action(); is the call so it needs the parenthesis. In this case, action is a reference to the actual method we wish to call. It also means you can pass any method.

And you will probably come back saying that the method can not be found and you are maybe missing a namespace or something of the kind, so add this on top:

  using System;