I've just found a stash of files that look like what I remember as InDesign tagged text, but they are from an experiment I didn't follow up at the time. I'd like to be able to pick up the project again.
Here's one tiny sample, which I have also found as an example in Kvern/Blatner/Bringhurst's InDesign CS5 book.
<ParaStyle:subhead>Travel through time to experience the greatest artistic performances in history!
<ParaStyle:para>We are pleased to announce our Summer 2007 series.
I can't see any specific Import option in InDesign 15.1.3 x64, and Place just places tags and all in the InDesign document. Hints and tips welcome!
And check the encoding. I used your code, added that line above just below <UNICODE-WIN>, edited the line to <UNICODE-MAC>, saved the text file with the Editor App on Windows 10 to UTF-16 LE and was able to place the file like that:
From my German InDesign 16 on Windows 10, import options showing: