shazdeh

This plugin adds an option page where you can add color options and the plugin hooks this elements to the Customizer where your client or theme users can customize the design.
Since 0.2 the custom designed panel to change colors is removed and now design tweaks are done through the WordPress Theme Customizer.

Color Manager

Enable your clients or theme users to easily change the color scheme of your design. With live preview!

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.

Color Manager vs Custom Color Palette for Gutenberg