ThemeZee

The Custom Color Palette plugin allows you to change the default color palette in the new WordPress Gutenberg Editor.
It replaces the color palette of WordPress Core and the theme.
<h4>Enable and change colors from three categories</h4>
<ul>
<li>Main Colors 
Primary, Secondary and Accent colors</li>
<li>Grayscale Colors 
White, Light Gray, Dark Gray, Black</li>
<li>Primary Colors 
Red, Green, Blue, Yellow, etc.</li>
</ul>
<h4>Requirements</h4>
This plugin only works with the new Editor. You have to use WordPress 5.0 or the <a href="https://wordpress.org/plugins/gutenberg/" rel="ugc">Gutenberg</a> plugin.
Note: Changing colors works with CSS variables and is not supported in outdated browsers like Internet Explorer.

Custom Color Palette for Gutenberg

A small and simple plugin to adjust the default color palette of the new WordPress Gutenberg Editor.

Kadim Gültekin

Do you want users to test color palettes of your Block Theme?
This plugin allows users to choose a color palette for the Block Theme from the frontend.
<a href="https://playground.wordpress.net/?plugin=block-theme-color-switcher" rel="nofollow ugc">Test with WordPress Playground</a>

Block Theme Color Switcher

This plugin allows users to choose a color palette for the Block Theme from the frontend.

Custom Color Palette for Gutenberg vs Block Theme Color Switcher