How can I allow users to specify image dimensions in CKEditor
Depending on how far you are in your project consider using Paragraphs instead, to have your content built modularly. Inline images are bad practice IMHO. They are difficult to preprocess and difficult to apply responsive image styles.

With Paragraphs (or in general with a fieldable approach instead like Kevin pointed out in the comments) you'd provide certain paragraph types, for example one for pure text and one for an image. Editor then places an image paragraph, followed by a text paragraph and the text simply floates around the image. You can have responsive image styles for the image, you can build the image field according your logic to provide certain crop types etc.



I know this is not the answer you might look for, but honestly for the sake of maintainability think about it if putting everything into the body field will still work in the long run. In my experience this can lead to a very big mess. Hard to disassemble, hard to migrate, hard to maintain.