This mod lets you open your Shulker Boxes from your inventory. Just right-click the Shulker Box in your inventory and it opens up. You can place it down by sneaking.
It is enough to install the mod on the server, but it can optionally be installed on the client for a better experience.
You need to install the mod on the server and the client.
The config file is located at config/shulkerbox/shulkerbox.properties.
The config file is located in your world folder in a subfolder called serverconfig and is called shulkerbox-server.toml.