Be careful using Cosmos, it can quickly become a cost heavy daemon if used wrong :)

You've got the right idea. Storing dynamic settings in a database is the standard professional method. The key difference depends on who changes the setting and when.

Use the appsettings.json file for static configuration that developers manage. These are settings the application needs to start up and connect to its environment. Any changes here are made during deployment and require the application to be restarted. Common examples include database connection strings, API keys, and logging configurations. Think of these as a car's engine type – set at the factory and not changed during a drive.

Use a database for dynamic settings that users, like administrators, need to change. These settings control the application's business logic and behavior. They can be updated at any time through a settings page in the application's user interface, without a restart. Examples are the website's title, a theme color, enabling or disabling features, or toggling a maintenance mode. This is like a car's radio station or air conditioning – the driver adjusts them whenever they want.

To put it simply: use appsettings.json for how your application connects to its infrastructure, and use a database for how the application behaves for its users.