Disqus allows most of the HTML tags in comments. Some of them are:
1. Italic<em> 2. Strikethrough<s> 3. Break<br> 4. Anchor<a> 5. Bold<strong> 6. Quotation<blackquote> 7. Paragraph<p> 8. Citiation<cite> 9. Section<span>
They also support Spoiler tags <spolier> which hide the text in your comments and reveal on hover or tap on mobile.