Sites support multiple versions, one of which is designated as the active version and accessible via https://yoursitesubdomain.cloudglusite.com
Non active versions can be accessed via https://yoursitesubdomain.cloudglusite.com/_v/<versionid> /end/point/path. You can get version ids from the console.
Use different versions to stage major updates to the site version components, give version specific url to your testers.
When you're ready to switch to the new platform set the active version on the site.
Read about version components: