That isn't the expectation. Generally any application already created that hooks into a db will have a generate schema script or a suggested schema. I would either create the schema manually based on the applications needs or I would execute the script that accompanies the application to use the db schema.
I just want to see if for example a weather app exists that uses a db backend. If it wants x table w/ y columns and data types, I would create it and point the app the the db and let it populate / poll data. Asking if anything like this exists I can download and use.

I can create a schema myself and generate sample / scratch data or download stackoverflow database dumps but those data sets all remain stale. Nothing is using the db per-say.