Hi,
If by 'flip vertically' you mean, for example, that a picture of a man is turned so that the feet are at the top and the head is at the bottom, I would just say 'It's upside down'.
If a page is flat on the table so that you can see the writing, and then you turn it over so that now you just see a blank side, we often say the page is 'face down'.
Best wishes, Clive