Use .xml-file from openstreetmap

I have downloaded an xml-file containing waypoints for a hiking track from
https://www.openstreetmap.org/relation/108816#map=15/49.2816/11.4918.
I have learned from the faq in osm, that the file is a gpx-file. My navigation app MAPs3D in iOS usually imports .gpx files without any problems. But there is no way to impofrt the .xml-file that I downloades from the osm-reference.

What can I do to show the downloaded route in my navigation app? Do I have to convertr the .xml to a .gpx? How to do?

Thank you.

You can do this with Overpass Query as in this example: http://overpass-turbo.eu/s/MPS - after that you can use export tool to get GPX file.

Just to make that clear: The *.xml file is not a gpx file. Those are completely different formats.