The classic block looks just like the classic editor, but it’s in block form. Also, custom or additional TinyMCE buttons are found in this block.
To add a classic editor, click on the Add Block button and select the Classic Editor block. Alternatively, you can start typing
/classic in a new paragraph block, then press enter.
Each block comes with unique toolbar icons and specific user controls that allow you to manipulate the block right in the editor. The classic block offers the ability to edit as HTML, duplicate, or convert to blocks.
Right after adding the block, you can edit the text you add as you would in the classic visual editor, using the tools and formatting options provided.
Clicking on the cog icon next to the publish button will toggle the visibility of this panel. While most blocks have specific options in the editor sidebar in addition to the options found in the block toolbar, the classic editor block does not have extra options.