Marat Nepomnyashy

Overview:
At the time of this writing, the latest version of WordPress, version 4.7, 
 has functionality to discourage search engines from indexing the whole site, 
 but not functionality to discourage search engines from indexing only certain 
 specific pages and posts of the site.
Robots Meta Whiz is a WordPress plugin that allows site administrators to 
 deploy custom meta robots tags to discourage search engines from indexing, 
 following links from, caching, indexing images from, and / or have 
 additional custom restrictions on only for certain specifically-designated 
 pages and posts.
It is an easy way to discourage search engines from indexing only specific 
 pages / posts.
This only applies to search engine robots, and will not effect the site’s 
 local search functionality.
Technical summary:
Plugin works by hooking-in special logic into the action ‘wp_head’ to inject 
 the tag <code><meta name='robots' content='...'></code> with restriction directives for 
 the specified pages and posts.
Official project URLs:
https://wordpress.org/plugins/robotswhiz 
 https://github.com/maratbn/RobotsWhiz

Robots Meta Whiz

Easy way to discourage search engines from indexing only specific pages / posts with custom meta tags.

Lukasz Jasinski

robots.txt is a file, which tell’s search engines, which parts of your site it can display publicly. 
This plugin add’s some entries to this file, to make your site safer from some attacks, keeping all your stength in seo intact ex. allowing search engine robots to harvest pictures for image search. When preparing a new site in WordPress, it’s one of the first plugins I install.

LJPL Armored robots.txt

Add some directives to your robots.txt file to keep your site safer

Robots Meta Whiz vs LJPL Armored robots.txt