With Smart Templates you can build dynamic pages from the contents included from different (source) pages

Pages are built dynamically and that means when the contents is edited on the source page, it is instantly refreshed on the page built with Smart Template

Here is online demo which uses the contents from Smart Templates space main page: ConfiTemplates Smart Templates and Excerpts app for Confluence

So, we have a smart template macro on ConfiTemplates Smart Templates and Excerpts app for Confluence

Then we have added another smart template macro on this page to use the contents from the smart template mentioned above

There is a little trick with how dynamic contents is rendered here... and we render it as if it is on the actual page (last parameter in Smart Templates macro)

For Smart Templates not using dynamic macros you can have it as unchecked (but this depends on the scenario)