cutch

Using either ctrl+c and ctrl+shift+v (Configurable from settings), or the the copy styles button in the block editor. Copy and paste the type and styles from one block to another. 
Ex. Click a header block, press ctrl+c (to copy), then click a paragraph block, and press ctrl+shift+v.
Note: For apple devices use the cmd key instead of ctrl. ex. cmd+c and cmd+shift+v.
<h4>Features</h4>
<ul>
<li>Convert to blocks which do not have a direct conversion</li>
<li>Copy styles from multiple blocks to another set of blocks, or one block to many</li>
<li>Retain block attributes during conversion. Ex. h6 for headings, or css classes.</li>
</ul>
<h3>Issues</h3>
Please post an issue in the <a href="https://github.com/Cutch/copy-blocky/issues" rel="nofollow ugc">GitHub Issues</a>

Copy Blocky

Copy and Paste Gutenberg blocks and styles.

John Cummings

If you’ve ever wanted to control how a particular part of your page or posts looks without having to modify the theme files or stylesheets, 
this is a simple plugin that allows you to do that.
Once installed and activated, you’ll have a new settings panel in the WordPress admin that will provide you with a text area block 
where you can include any styling you’d like to use, and a second input field that allows you to insert a comma delimited list of page 
or post IDs to apply these styles to.
Alternatively, you can enter ‘ALL’, and have your styles applied on every page/post.
Bug Reports or Feature Requests 
https://trello.com/b/9Bio6kHl
Follow me on Twitter 
https://twitter.com/jcummings1974

CSS Theme Override

Adds a settings panel to the Wordpress admin that allows you to specify css class or id styles and pages/posts to apply them to.

Copy Blocky vs CSS Theme Override