Jan Štětina

Includes custom HTML/CSS/JS code in the section on every blog in the network.
Very simple, but sometimes useful plugin.
After activation visit Network Admin –> Settings –> Multisite wp_head Code for setup. Nothing else is needed.
Developed for private use, but has perspective for more extensive usage. I can’t guarantee any support in the future nor further development, but it is to be expected. Kindly inform me about bugs, if you find any, or propose new features: <a href="mailto:zaantar@zaantar.eu?subject=[multisite-wphead-code]" rel="nofollow ugc">zaantar@zaantar.eu</a>.

Multisite wp_head Code

Includes custom HTML/CSS/JS code in the  section on every blog in the network.

Dead Writers Society

Light and fast wp_head() cleaner. Just activate it and all unnecessary code will be deleted from site header section. It will improve loading speed of your website.
This plugin will remove:
<ul>
<li>WordPress version</li>
<li>shortlink</li>
<li>Really Simple Discovery link</li>
<li>RSS feed links</li>
<li>all extra RSS feed links</li>
<li>wlwmanifest.xml</li>
<li>meta rel=dns-prefetch href=//s.w.org</li>
<li>the next and previous post links</li>
<li>Emoji icons</li>
<li>WordPress REST API</li>
<li>oEmbed</li>
</ul>
Feeds (RSS, RSS2, Atom & RDF) and comments feeds will be disabled and redirected to home page for security reasons.

Nietzsche – WP Head Cleaner

This plugin cleans up the wp_head() and removes unnecessary code.

Multisite wp_head Code vs Nietzsche – WP Head Cleaner