Edward

Enables the display of custom-field variables in the WordPress post editor via a TinyMCE button. Works well with custom post types as well as default post types.
Use the TinyMCE button to choose from a list of custom fields attached to the post to insert, or manually specify a custom field to display using the following syntax:
<pre><code>{%custom_field_name%}
</code></pre>

Custom Field Variables

Enables the display of custom-field variables in the WordPress post editor via a TinyMCE button. Works well with custom post types as well as default  …

Andrew Ozz

This plugin is intended for more advanced users that would like to change the default TinyMCE configuration in WordPress. 
It makes it very easy to add, remove or change all TinyMCE settings for the classic editor and for the classic block in the block editor.

Advanced TinyMCE Configuration

Set advanced TinyMCE options for the classic block and classic editor.

Custom Field Variables vs Advanced TinyMCE Configuration