Recopilation of Azure AD B2C use cases I use to find in customers, or are requested by peers.
When working with custom policies, I'm always using the custom policies starter pack available here https://docs.microsoft.com/en-us/azure/active-directory-b2c/active-directory-b2c-get-started-custom#download-starter-pack-and-modify-policies
For practicity, I only describe what you need to add or edit, depending on the case. In other more complex cases, I'm going to publish the sample policies involved.