Select Home > Styles (or press Alt+H, then L), and then select the heading you want, such as the Heading 1 button. Word applies a font and color change to help make it clear that this is a title -- the Heading 1 of the article. The next heading type is a Heading 2. Want More? Accessibility in Microsoft 365. More @Wikipedia
Hover over any link to get a description of the article. Please note that search keywords are sometimes hidden within the full article and don't appear in the description or title.