Let me simplify this for you.
Wix has two different website editors - i.e. the Wix Editor and the Studio Editor.
The Wix editor is the legacy editor that offers basic features that can help you get your site up and runnning for a low price. If you develop a site using the Wix editor, you will have to upgrade it to premium by purchasing one of the Wix Editor Premium Plans. You do not get any revenue share for each site that you upgrade to premium (unless you’re legend level), but you do get 100 points added to your partner profile.
If you / your client needs a website with advanced functionalities such as a responsive layout, custom scroll interactions, and a site that overall looks professional and visually appealing, then it is recommended that you develop it using the new Studio editor, which has these capabilities, along with many more features that the legacy editor does not have. When you want to upgrade a site that you’ve built on Wix Studio, you can choose from one of the Wix Studio Premium Plans, which are comparatively expensive than the latter, but if you upgrade your site using one of these plans, you can earn a 20% revenue share (30% if legend level), along with 300 points for each Studio site that you upgrade to premium.
Wix has announced this just a few days ago, but they have not provided a fixed date for the same, so its hard to guess.