It appears as the special meta-box named “.DOCX Source” under the main editor. All changes will be put to the particular editor places.
External linked images can be uploaded by choosing folder that contains it.
How to set particular attributes see here.
Classic editor is fully supported including post body, title, slug, featured image, excerpt, categories and tags.
Gutenberg editor is also fully supported.
By turning off ‘Use Gutenberg formatting’ classic content will be inserted rather than using Gutenberg blocks.