unity getting a child script from a gameobject code example

Example 1: how to reference a child object unity

private void Start()
    {
        parentObject = GameObject.Find("Parent");// The name of the parent object
        childObject = parentObject.transform.GetChild(0).gameObject; // the parent index (starting from 0)
    }

Example 2: unity how to get a child from a gameobject

//For unity engine
GameObject.transform.GetChild(The child index).transform;