Jonas Hjalmarsson

A single shortcode you can drop into any post, page, or text widget to get a click-to-expand “read more” toggle. The output is a native HTML <code><details></code> element styled with a small inline stylesheet — nothing else.
The point is the absence of features. There is no settings page, no animation library, no editor block panel with twelve toggles. If you need a read-more on one paragraph in one post, you do not want a plugin that wants to manage your whole site.
Usage:
<pre><code>[expand title="My title"]
The content goes here.
<img src="even-images-can-go-in-here.jpg" />
And wrap up with a closing expand tag.
[/expand]
</code></pre>
Supports a custom CSS class via <code>[expand class="my-class"]</code> and works with WordPress oEmbeds and other shortcodes nested inside.

Simple Expand – Lightweight Read more toggle

Adds an [expand] shortcode that wraps content in a native HTML `` toggle. No JavaScript, no settings page, no bloat.

Brijesh Mishra

Show required content and let user click on read more. Visitors will see readmore link on the page, when they will click, rest of the content appear with very simple animation on the same page.
Features
<ul>
<li>This plugin will effect only on pages</li>
<li>Select check box to show read more on the pages</li>
<li>Control option shows on all pages, you can select to show readmore on the page</li>
<li>Define the width to show from the page.</li>
<li>Very simple and easy to use</li>
</ul>

ReadMore ReadLess

ReadMore ReadLess will hide content on page.  Clicking on readmore will show complete page without refreshing the page.

Simple Expand – Lightweight Read more toggle vs ReadMore ReadLess