In addition to the many things you can do in a note such as linking to Substack posts, mentioning other writers, or adding an image, you can easily format text.
When composing a new note on the web, type and then highlight the text. A toolbar will appear and you'll see options to bold, italicize, strikethrough, quotes, bullet lists, and more.
Check out an example of how a formatted note appears in the Home feed: