Cernocky

The Custom Post Styles plugin is an easy way to customize css of your posts individualy using CSS code. 
Plugin adds css editor box in your post editor.
See it in action: 
https://vimeo.com/179525212
Improve the user experience for your readers without having to change theme code.
<h4>Possible upcoming features</h4>
<ul>
<li>Better CSS editor</li>
<li>Custom webfonts</li>
<li>Supporting more post types</li>
<li>Custom styles for posts by categories, authors etc.</li>
<li>Visual editor</li>
</ul>

Custom Post Styles

Allows you to add custom css styles to posts.

Ajay Kumar

Quick Child Theme Generator is a very easy, quick and user friendly plugin to create a child theme for any theme supported by WordPress CMS. It allows you to edit or add functionality to your template without having to overwrite any of the parent theme files and it will helpful for restrict losing data on WP update time. You do not need to deal with any code and configuration to create child themes. It will reduce your <code>time</code> and <code>effort</code> to create a child theme.
This plugin is providing you a way to create basic custom templates pages, those will help you to add custom code in specific pages.

Quick Child Theme Generator

Quick Child Theme Generator is a WordPress plugin and it is helpful for creating child themes quickly.

Custom Post Styles vs Quick Child Theme Generator