When you’re creating your Google document, it’s normal to divide your content into sections, each one having its own heading. The default heading styles provided by Google are fine in the majority of cases.
However, if you ever want special formatting, you can make your own heading styles and apply them to any text in your document.
To create a new style of heading, all that’s required is to format your text in the way you want it to appear, and then highlight it. Next open the Styles drop-down menu; hover over the style you wish to modify, and click the arrow icon next to it; and finally select Update.
Elsewhere in your document, when you want to apply the same style, you can simply highlight text and set the style using your modified format, using the Styles menu, as normal:
Notice how the item in the drop-down menu has changed its appearance to reflect your modified style.
This change will only apply to the current document, so you won’t lose the default styles for other documents or users.