Tested out the Azure AD B2C PKCE Authorization Code Flow in Postman. You can follow the tutorial and example below:
Postman workspace example
Public docs
Tag Archives: Oauth2.0
Oauth2 and OpenID Protocol Review
The following presentations by John Craddock and Pamela Dingle at Microsoft Ignite are the best explanations I have found for understanding and troubleshooting the Oauth2.0 and OpenID protocols as they related to Azure Active Directory in increasing order of complexity: