Jonathan Brinley

The standard excerpt field will appear on pages, just as it does on posts.
Additionally, there is a new widget to display the excerpt of a selected page.
Created by <a href="http://flightless.us/" rel="nofollow ugc">Flightless</a>

Page Excerpts

The plugin is built for something very specific, and does it perfectly.

Simple but effective

Adds an excerpt field to pages, and provides a widget for displaying page excerpts

J0SiE

Created to help those people who don’t like to edit code in template files (or are too lazy to do that). 
Just activate the plugin and it will automatically show the_excerpts in your homepage, archives and search results. 
It tries to display your custom excerpt text and if it doesn’t find it it will show an automatically generated excerpt. 
You can also define excerpt length, custom read more link and attach a thumbnail.

Auto Excerpt everywhere

Thanks to author for creating this plugin. 
It's works out of box. And working fine at WordPress Version 4.6.1


Works out of the box on WP Version 4.6.1

The plugin automatically displays excerpts instead of full post contents in your blog. Custom excerpts and generated excerpts supported.

Page Excerpts vs Auto Excerpt everywhere