Answer to your question is yes to some extent.
1. If we make changes to the "Structure/Content policy" that would get reflected on the page using this template.
2. But,if any changes are made to "Initial content" then changes would not get reflected to already created page whereas if new page would be created, then that new page will have this new changes.
3. Any we make changes to "Layout" depending on the component that are part of Structure or Initial content that would get reflected on the pages accordingly.
Reference Link:- Experience fragment, is content editable after adding in page?
~kautuk
Kautuk Sahni