Josh Pollock

Use this plugin to create a demo site for your themes, or use it to allow users to customize the presentation of your site.
The JP Theme Bar Plugin adds a theme switching bar to the bottom of your site, perfect for theme preview sites. The settings page for the plugin lets the end user choose which themes to add, as well as set the colors for the theme bar. You can see it in action on this site.
New in version 0.0.3 -> Themes will update theme mods when changing themes allowing for individual theme settings to be previewed properly.
This plugin is based on the <a href="http://iainjmccallum.com/wordpress/live-demo-theme-bar/" rel="nofollow ugc">IJM Theme Switcher Bar v2.0</a> by <a href="http://www.iainjmccallum.com/" rel="nofollow ugc">Iain J McCallum</a>
IMPORTANT- The plugin <a href="https://wordpress.org/plugins/theme-test-drive/" rel="ugc">Theme Test Drive</a> by <a href="http://www.prelovac.com/vladimir/" rel="nofollow ugc">Vladimir Prelovac</a> must be installed and activated in order for the theme switching to work.

JP Theme Switcher Bar

Adds a theme switcher/ theme demo bar to the bottom of your site to allow users to switch the theme they see on your site.

Jael Meire

Easy Dark Theme for Astra adds a light/dark mode switcher designed specifically for Astra themes.
Main features: 
* Toggle control mode: 
 * Auto (system preference) using prefers-color-scheme 
 * Button mode (user switch) 
 * Optional “Remember preference” (persists user choice) 
* Toggle placement options (floating): 
 * Bottom-right, bottom-left, top-right, top-left 
 * Horizontal and vertical spacing (positive values, automatically applied based on position) 
* Toggle visibility options: 
 * Always show, hide on mobile, hide on desktop, always hide 
* Toggle style options: 
 * Icon or Text 
 * Pill style: 
 * Capsule switch with sun/moon icons and animated knob 
* Optional theme transition: 
 * Smooth transition applied only while switching between themes 
* Multiple toggle outputs: 
 * Floating button (auto-injected) 
 * Widget 
 * Shortcode: [edta_toggle] 
 * Admin preview with live style switching 
* Optional Astra Global Colors mapping: 
 * Free Preset Palette (included, not editable) 
 * Custom Palette (fully editable) 
 * Dark palette always applied in dark mode 
 * Light palette can be skipped to respect the theme’s own light colors (recommended) 
* Accessibility options: 
 * Reduced motion support (respects prefers-reduced-motion) 
 * Optional focus ring improvements for keyboard navigation 
* Tools: 
 * Export settings to JSON 
 * Import settings from JSON 
 * Reset settings to defaults (with confirmation) 
* Admin UX improvements: 
 * Reduced flicker on initial load (palette + lock state handling) 
 * Improved state synchronization for preset/custom palettes 
 * Improved save-state detection in sidebar
Notes: 
* This plugin is intended for Astra themes. If Astra is not active, the plugin’s frontend output is disabled. The admin page remains available.
Plugin page: 
https://wordpress.org/plugins/easy-dark-theme-for-astra/

Easy Dark Theme for Astra

Easy light/dark mode for Astra with a toggle button and optional palette mapping to Astra Global Colors.

JP Theme Switcher Bar vs Easy Dark Theme for Astra