Append image style to an inline image in CKEditor
Use insert module 


  Insert is a utility that makes inserting images and links to files
  into text areas or WYSIWYGs much easier. It adds a simple
  JavaScript-based button to FileField and ImageField widgets. When used
  with ImageField and ImageCache, images may be inserted into text areas
  with a specific ImageCache preset.
  
  This module was previously known as FileField Insert.
  
  Features

Support for all major WYSIWYG editors, including tinyMCE, CKeditor, the WYSIWYG project (the recommended approach), and plain

  
  text areas.
      Insert images using ImageCache presets
      Maximum width setting for inserted images (for combined use with the Image Resize Filter module)
      Per-field insert configuration


I used that on drupal 7 in several projects and it's what you want.I don't used Drupal 8 version yet,but hope works well.

Hopefully, in Drupal >= 8.8 it's on the core. 

https://www.drupal.org/docs/8/core/modules/media-library-module/embedding-media-with-ckeditor