Syntax Highlighting for inserts PHP, HTML, CSS or JS code on your site.

You can download it and install from catalog of plugins, here: https://wordpress.org/plugins/lite-syntax-highlighting/

Also you can use it on every site, without plugin.
Just connect the js and css files and try to write:

<pre class="slh__php">CODE</pre>
<pre class="slh__html">CODE</pre>
<pre class="slh__css">CODE</pre>
<pre class="slh__js">CODE</pre>