Editora 0.18.3. Archived, so links from that release keep working. Read the 0.18.5 page →
Typst: Emphasis
typst.emph Wrap the selection in _emphasis_ markup.
How to run it
Open the command palette (M-x in the Emacs keymap) and search for Typst: Emphasis, then press Enter. It has no default keybinding, but you can bind one in Settings → Keymaps.