Features live in modules nowadays, if you do not add corresponding bundledModule / bundledPlugin dependencies - your build does not see them in compilation and at runtime too. It should be basically the same as with IntelliJ Community.
With IntelliJ Community it also never was truly the platform, as it bundles a lot of JVM specific plugins anyway
Platform APIs between free/paid almost do not change. E.g LSP and DAP always available regardless the license status.