Lemmy-ui uses markdown-it-sup, so I think superscript should work on a single word like this: superscript . It won't work if there is a space in the superscript text: ^this wont work^ . Each word must be enclosed with superscript tags: thisshouldwork
I installed Sync just to test this. To me, that's displaying with "not" superscript but not "working". On web, it just doesn't work at all (this is due to the markdown library lemmy-ui uses not allowing spaces).
Suspect ~subscript will~ also not work. Curious about struck-out text.