João Carmo Pereira

This plugin will add a new copy to clipboard functionality to Gutenberg Code Block. 
It will add a copy button at the top right corner of the block. After clicked, it will select the text, copy to clipboard, and after copy it will deselect the copied text. No markup here.
This plugin makes use of two javascript libraries: 
Clipboard.js and Prism.js

Carmo Copy to Clipboard

This plugin will add a new copy to clipboard functionality to Gutenberg Code Block.

hashsalacop

A simple plugin that allows you to copy or cut paragraphs from your site’s main content to the clipboard to use elsewhere. or you can customize depends on your needs
Plugin Features: 
1. Copy Content and paste 
2. Copy and Cut content and paste 
3. Its easy to use. 
4. Tested up to latest WordPress

CLIPBOARD

A simple plugin that allows you to copy or cut paragraphs from your site’s main content to the clipboard to use elsewhere.

Carmo Copy to Clipboard vs CLIPBOARD