Dark Version

HTML
You can simply change layout mode to Dark by doing the below changes in the file src/html/default/partials/body.html.
Simply set the attribute data-layout-mode="dark" to the html tag. It will update the layout mode to Dark mode. No need to change any css or js files.

Laravel
To have dark mode enabled, replace the reference of bootstrap.min.css stylesheet file to bootstrap-dark.min.css and app.min.css to app-dark.min.css
in the resources/views/layouts/head-css.blade.php and make sure to update the public/js/app.min.js has initSettings() function which you need to comment out. Because it will set to default the light version.