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?
Recent comments
@yorkshirepudding, In the end I fixed it by deleting the config/active folder contents, copying the config/staging/ files into config/active, importing the database again and clearing the caches...
Importing the staged config throws an error: another field with the same name already exists
Thanks, I have to go out now, I will try later on and report back
Importing the staged config throws an error: another field with the same name already exists
Hi Francis. Yes, what config do you have in staging for it? You might have configs like: field.field.field_video_embed field.instance.node.page....
Importing the staged config throws an error: another field with the same name already exists