The documentation for Page.Rect says:
Page crop box is returned if specified, otherwise page media box is returned.
Does GetPageRect do the same? The documentation does not specify.
We have shared our response in reply to your other similar inquiry. You may please check it.
As shared in other thread, Page.Rect takes crop box into consideration and if not present then media box. However, if you want to consider rotation while determining page rectangle, you can use Page.getPageRect(bool considerRotation) method.