Creating hidden pages or page templates
You can create your own page templates in a Plasmic project, or just mark any page to prevent it from being published with others.
Just create a normal page,
but set its name to begin with an underscore—for example,
Any pages with a leading underscore will not be published (so it doesn’t matter what page route you set on it).
To create a new page based on that template, simply right-click and duplicate the page from the project list in the top-left of the Studio.