To return more than just your defaults, you will need to define the sources you want considered during a value lookup. The order or declaration, will determine the order they are queried in.
This example prioritizes secrets manager above all, then environment variables then a hard coded set of default values.
To get raw values, you can use a simple get operation.
const myConfig: any = await Configurations.get('a-value');
To cast as the values are returned.
const myConfig: string = await Configurations.as.string('a-value');