UNITY auto size ui set max width

gistfile1.txt

// Not work on Awake
private void Start()
{
    var rect = gameObject.GetComponent<RectTransform>();
    if (rect.rect.width > ScreenSizeHelper.MaxWidth)
    {
        var height = rect.rect.height;
        rect.anchorMin = new Vector2(0.5f, 0.5f);
        rect.anchorMax = new Vector2(0.5f, 0.5f);
        rect.sizeDelta = new Vector2(ScreenSizeHelper.MaxWidth, height);
    }
}