File under quick and dirty, but works for me.
The issue is that I have an utterly unreadable XML file in front of me. Not only is there no indentation, I don’t even have any line breaks.
To format it for readability, first insert line breaks
Then load and apply the XML indent file
:set filetype=xml :filetype indent on
And apply it
There are probably better ways of achieving the same end, but as a quick fix, this works for me.