Nikolay Bachiyski

In WordPress you can set individual templates for pages, which allows you to easily include additional functionality. Unfortunately this feature is not available for posts. Here is where this plugin comes.
After installtion you will be able to choose a template for each post the same way you do with pages.
You can find <a href="https://codex.wordpress.org/Pages#Creating_Your_Own_Page_Templates" rel="nofollow ugc">how to your own templates</a> in the Codex.

Templates for Posts

The same as page templates, but for posts.

Spencer Brown

This plugin offers you the ability to add custom page template files to your WordPress installation without having to manage 
theme folders or use a ftp client. Simply upload the custom template file you have been working on and it will be registered 
with WordPress as a template option for your pages. This plugin is straight to the point and has a clean user interface using 
W3.CSS.
Plugin menu is located under ‘Appearance’ menu.
Attribution: This post online and code on github by wpexplorer: 
http://www.wpexplorer.com/wordpress-page-templates-plugin/ 
https://github.com/wpexplorer/page-templater

Custom Page Templates Setup

Easily add custom page templates without having to use ftp or keep track of changing themes.

Templates for Posts vs Custom Page Templates Setup