Theme Candy is a Blender addon by Armored Colony for recoloring the interface without changing UI elements one at a time. A single color wheel changes the entirety of Blender's UI color, and the addon can sync your viewport selection colors with the UI.
Beyond the main color wheel, Theme Candy lets you adjust Edit Mode selection colors independently and change panel colors for a different look. An Advanced mode adds extra controls for fine-tuning, while important theme options stay readily accessible. The developer describes it as fun and easy to use.
It supports Blender versions 4.2 through 5.0 and is released under the GPL license. The addon holds a five-star rating across seven reviews and has sold more than 400 copies. A demo video is available, and documentation is included.