Is the Xray App for phones true?

No, for many reasons. Firstly xray images require a concentrated burst of radiation and a scanner that can read and interpret those signals. Secondly, if a phone could deliver bursts of x-ray radiation, it could be used as a deadly weapon. Third, if for some reason it *did* have all of these features, it would kill the battery dead in less than a minute. So no, they're scams or photo filters applied over the video to make it look legitimate.