To enhance the WordPress default formatter’s flexibility, this plugin 
enables configuring content and excerpt styles with various formats.
<h4>Features</h4>
<ul>
<li>Replaces “br” tags with “p” tags.</li>
<li>Produces valid XML parser for all sources.</li>
<li>Automatically generates excerpts in chosen length. Enables configuring following settings; length, separator elements (period, 
touten, paragraph), read more text, tags which you allow in excerpts, 
and etc..</li>
<li>Add any tags or texts to one’s contents as header and footer.</li>
</ul>
<h4>Demo</h4>
See this plugin working on <a href="http://www.wembley.jp/" rel="nofollow ugc">my blog</a>. Contents and excerpts in this site are generated by this plugin.

Plastic Post Style

記事本文と抜粋の出力を調整・カスタマイズします。Configure content&excerpt styles of all posts with various configurations.

Jonathan Desrosiers

Linchpin

Aaron Ware

Note: This plugin does not support the block editor but should continue to work without issue when using it with custom post types and the <a href="https://wordpress.org/plugins/classic-editor/" rel="ugc">Classic Editor Plugin</a>.
Before WordPress displays a post’s content, the content gets passed through multiple filters to ensure that it safely appears how you enter it within the editor.
One of these filters is <a href="https://codex.wordpress.org/Function_Reference/wpautop" title="wpautop" rel="nofollow ugc">wpautop</a>, which replaces double line breaks with <code></code> tags, and single line breaks with <code> </code> tags. However, this filter sometimes causes issues when you are inputting a lot of HTML markup in the post editor.
This plugin displays a checkbox in the publish meta box of the post edit screen that disables the <a href="https://codex.wordpress.org/Function_Reference/wpautop" title="wpautop" rel="nofollow ugc">wpautop</a> filter for that post.
Also adds a ‘wpautop’, or ‘no-wpautop’ class to the post_class filter to help with CSS styling.

Toggle wpautop

Easily disable the default wpautop filter on a post by post basis.

Plastic Post Style vs Toggle wpautop