Using Cookieplone to connect to an existing Postgresql relstorage

I want to set up a new Plone site using Cookieplone and ensure that it points to an existing Postgresql database for relstorage. Looking for pointers.

As far as I can see, I'll need to make changes to the configuration files in the backend/instance folder

I think there is an instance.yaml file in the backend folder, which can be customized to your needs. See this post for configuration hints: [solved] RelStorage with MySQL on Plone 6 - #9 by 1letter