Unity : How do you add gameObject as child to other?

GameObjectAsChildToOther

[SerializeField] GameObject towerParentTransform;

private void InstantiateNewTower(Waypoint baseWaypoint)
{
  var newTower = Instantiate(towerPrefab, baseWaypoint.transform.position, Quaternion.identity);
  newTower.transform.parent = towerParentTransform.transform; //THIS LINE 
}

//or better

[SerializeField] Transform towerParentTransform;

private void InstantiateNewTower(Waypoint baseWaypoint)
{
        var newTower = Instantiate(towerPrefab, baseWaypoint.transform.position, Quaternion.identity);
        newTower.transform.parent = towerParentTransform; //THIS LINE
        baseWaypoint.isPlaceable = false;

}