gozerstudio

<a href="https://github.com/doginthehat/postinpost" rel="nofollow ugc">Post In Post</a> provides an interface to import posts in other posts
Requires PHP 5.2 or higher, WordPress 3.3 or higher.
Features:
<ul>
<li>Customisable per post type</li>
<li>Import post content inline or as a shortcode</li>
<li>Import full or excerpt post content</li>
<li>Safety mechanism again infinite nesting of posts.</li>
</ul>

Post In Post

David Klhufek

This simple plugin adds useful buttons to the native WordPress HTML editor (Classic Editor).
Currently adds: 
h1, h2, h3, h4, h5, span, hr, nbsp, mox
The “mox” button adds a nice responsive CSS class which you can use to highlight pictures or other elements in your posts.
Note: This plugin works only with the Classic Editor. It does not support the new Gutenberg (Block Editor).
<h3>Compatibility</h3>
<ul>
<li>Requires the Classic Editor to be active. </li>
<li>Designed specifically for the HTML mode of the editor.</li>
</ul>

Quicktags for WP

This simple plugin adds useful buttons to the native WordPress HTML editor.

Post In Post vs Quicktags for WP