Often times, headings are meant to emphasize or enlarge only a few words.
If you want to add content in paragraph format, you can add a paragraph using the paragraph element
<p>The Nile River is the longest river in the world, measuring over 6,850 kilometers long (approximately 4,260 miles). It flows through eleven countries, including Tanzania, Uganda, Rwanda, Burundi, Congo-Kinshasa, Kenya, Ethiopia, Eritrea, South Sudan, Sudan, and Egypt.</p>
Paragraphs are great for expanding the amount of content (text) on your web page. As you begin to add more text to your web page, however, keep in mind that large amounts of text in paragraph format can overwhelm web page visitors. For example, if multiple paragraphs on your web page each contain large amounts of text, your web page could become difficult to consume.