If the localScale is changed on a child GameObject (but not the parent), only the child's scale will change. However, if the parent's localScale is changed, all the child GameObjects scale will change as well.
public class ExampleClass : MonoBehaviour
public float x = 0.1f;
public float y = 0.1f;
public float z = 0.1f;
// Widen the object by x, y, and z values
transform.localScale += new Vector3(x, y, z);