According to the release notes, these ideas were delivered:
FR-2057 / FR-2373 Allow easy installation of CKEditor plugins / Support "Paste" of Image in CKEditor (without URL or uploading the image)
I wonder how this was delivered. Copy-paste an image is still not possible. I Tried Windows Snip & Sketch to paste a captured image in the RTE item on apex.oracle.com without success.
The raw html is not going to work, because it has a maximum of 4000 characters, so putting the base64 code there isn't going to work.
Even if it did, you would first need another tool to convert an image to base64.
For the rest, I didn't see anything in the release notes that looks like support for " easy installation of CKEditor plugins".