Many inbuilt Word styles are hidden until they are used but there’s a way to force hidden styles to appear right away.
The most obvious example of ‘Hide until used’ styles are the Heading styles.
Word initially shows only the first three headings ‘Heading 1’, ‘Heading 2’ and (drumroll) ‘Heading 3’. Hidden away are Heading style 4 to 9. You can see all the styles, hidden or not in Manage Styles lists.
Normally the ‘Hide until used’ styles appear as needed. For example, Heading 4 will show up if you’ve used ‘Heading 3’ in your document.
When setting up a document or template, you want those styles to show up as you’re configuring the Style Gallery, Quick Access Toolbar or even ribbon.
Do that from Manage Styles | Recommend. Select the style then choose ‘Set whether style shows when viewing recommended styles’ to Show.
Tip: the default list is style priority order (the order of styles in the styles pane and gallery). Changing the sort order to Alphabetical makes styles easier to find on the long, long list.
This is also the place to change the order of styles in the recommended Style Pane and Style Gallery lists. see Style Priorities in Word’s Style Gallery and for our Mac friends Style Priorities in Word for Mac