tinymce-docs/_includes/configuration/image_advtab.md

image_advtab

This option adds an "Advanced" tab to the image dialog allowing you to add custom styles, spacing and borders to images.

Type: Boolean

Default Value: false

Possible Values: true, false

Example: Using image_advtab

tinymce.init({
  selector: 'textarea',  // change this value according to your HTML
  plugins: 'image',
  menubar: 'insert',
  toolbar: 'image',
  image_advtab: true
});