Christopher Finke

Formategory allows you to customize posts based on their categories. Just define a template for a category, and all of the posts in that category will be displayed according to the template.
Use the buttons in the top-right meta box to insert placeholders for the post’s content; {{ the_content }} will be replaced by the post’s content, and {{ the_title }} will be replaced by the post’s title. Select some categories for the template, and after you save it, any posts in those categories will be instantly templated.
The “Category Templates” page in your dashboard allows you to manage your templates just like you manage your posts and pages.

Formategory

WordPress Monsters

You can create templates (layout) for your pages to add some blocks of content before/after general content.
Also you can assign your template to custom post type(archive or single), taxonomies, 404 and search results pages, this options can be found in Templates->Settings menu in admin console.
You should use
<pre><code>[wpm-template-content]
</code></pre>
shortcode in this templates to separate content.
Watch how to use Template Manager plugin in this cute short video:
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Template Manager by WordPress Monsters

This is a temlate manager plugin for easy WordPress development from scratch when you are use Page Builders plugins.

Formategory vs Template Manager by WordPress Monsters