The examples need to be configured with an OpenID Connect issuer (or Authorization and Token endpoints manually), and the OAuth client information like the Client ID and Redirect URI.
Each example has docs on how to configure:
To get the Issuer, Client ID, and Redirect URI, for your particular IdP, you may view the IdP-specific information in the next section.
All Certified OpenID providers that support RFC 8252 are welcome to submit a README with IdP information.
Those with instructions on file: