Adding formatting to your stories is perfectly possible and already configured for you by default.
Go to a story editor and by selecting a piece of text (a word, a sentence, a paragraph...) the formatting toolbar will appear. These are the options available:

Bold
Italics
Underline
Small text
Create links (to external sites, or to headings)
H2 heading
H3 heading
H4 heading
Create a quote out of the selection
Create a bullet-point list out of the selection
Create a numbered list out of the selection
Create a comment out of the selection (more info)
For links, you have the option to open the link in a new window and/or set it as a nofollow hyperlink. There are four options to choose from:
External: links to a different website or page.
Section: links go to a heading (useful for creating a table of contents, more info).
Email: mailto links to allow visitors to create a new email with your chosen address.
Phone: a phone number that when clicked on will call using the visitor's default calling software.

📚 Next steps?