You can do it manually. Simply create a new project of the type you need and duplicate the slides of the source project in the new one.
- Create a new course.
- Open the existing course and duplicate the slides by clicking on the “duplicate slide in another subsection” icon.
It will be copied with all the elements and functionalities that integrate it but with the new design style of the chosen template (some elements will change their view).
Keep in mind the specificities explained in this article: Other actions you can do with your slides - isEazy help center