A resource pack (RP) contains a starter set of services and policies for a specific use case. They eliminate the need for you to install a plugin, deploy and configure one or more experts that use that plugin and the policies that go with it. By installing the resource pack, all of these are done automatically.
Most resource packs are intended as a one time installation; once installed, you may want to change the settings and/or policies and you do not want to undo any of your changes.