Fullscreen for CKEditor 5 classic editor build

npm i -D @ckeditor/ckeditor5-core
npm i -D @ckeditor/ckeditor5-ui

Include in your ckeditor.js

import FullScreen from './FullScreen';

Include in the plugin List ClassicEditor.builtinPlugins = [ .... FullScreen, ];

And include it in your toolbar

ClassicEditor.defaultConfig = { toolbar: { items: [ ....., 'fullScreen' ] },