Look into Building Blocks including Cover Pages and AutoText.
Automated Boilerplate Using Microsoft Word
Word does not really see or use "pages" as a unit.
Rather than "applying a template" consider simply creating Word
templates for what you want to do and creating new documents or templates based on those
templates. "Template" is a jargon term in Word with a very specific meaning.
When creating templates for others, pay attention to
Styles,
[Quick] Style Sets, and
Themes. They can make your creations much more useful and flexible.