I think you will have to wait for a while after the release because I assume there are refactorings being made to the code now during the betas and probably a few adjustments after the first release.
I have not seen anything yet in the CMS that I could not reproduce from V4, but there are changes to the CSS classes now that we have a built-in dual theming for the light and dark modes. You also have some updates to the tabs and collapsible items, but they are basically the same.
I suggest you set up a test environment and try things out.