Combine Formatting Layers
The most readable announcements combine a few techniques rather than piling on one. A common structure is: an emoji-letter word as the title, a Markdown header with the event name, a short paragraph, then a bullet list for details. Discord's # header, **bold** text and - lists do most of the work, and the emoji letters add personality at the top.
Boxtype's Message Formatter builds the Markdown part with buttons, and the converter makes the emoji title.