This is basically the respective issue for what is being worked on for D8 core here: https://www.drupal.org/project/drupal/issues/2061377
This is part of #1087 and #378, and related to #2841

Original issue summary
It would be great to be able to use image styles within CKEditor so that users could get consistent image sizes/styles within their content.
This is a follow-up from #2010 and #2630 where @Dinornis commented:
Maybe the image sizing can be replaced with the option of selecting an Image style predefined in
/admin/config/media/image-styles?
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