You’ve seen the Quick Styles gallery, which includes styles that are designed to look good together. This is just one of the many style sets available in Word. You can apply a whole different set of styles, if you want, by choosing a different style set.
To view the other style sets:

Click
Change Styles on the
Styles group on the
Home tab of the
Ribbon.

Select
Style Set.

View your different style options.
You don’t have to change the style to see how it will look. Instead, point to each Style Set to see how it will appear in your document.
Although every style set likely contains all of the styles that you need to build a document, you may want to add a brand new style or modify an existing one.