Check out example codes for "unity get all children". It will help you in understanding the concepts better.

Code Example 1

foreach (Transform child in parent) {
  //Your code
}

Code Example 2

foreach (Transform child in transform)

Code Example 3

GameObject Child;
Child = transform.GetChild(0).gameObject;

Code Example 4

public List<GameObject> childrens = new List<GameObject>();

    void Update()
    {
      foreach (Transform child in transform)
      {           
          if (!childrens.Contains(child.gameObject))
          {
              childrens.Add(child.gameObject);
          }                            
      }
    }

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