While Craft 3 is in beta, you'll need to install plugins with Composer. If you've installed Craft 3, you should already know a bit about Composer.
To install Expanded Singles, follow the below instructions.
Open your terminal and go to your Craft project:
Then tell Composer to load the plugin:
composer require verbb/expanded-singles
In the Control Panel, go to Settings → Plugins and click the “Install” button for Expanded Singles.
To edit settings, go to Settings → Expanded Singles.
Available for Craft 2 & Craft 3, unlimited use, free forever.