Only yesterday I encountered a fantastic example. I have to implement an API, there is a swagger/openAPI doc for it, but still, the real interaction and meaning

Only yesterday I encountered a fantastic example. I have to implement an API, there is a swagger/openAPI doc for it, but still, the real interaction and meaning of the calls can be a bit hard to grasp. But the developers provide an example application (in C#). I expected something basic that implements the login flow and some of the more important calls. Instead I found something that could be described as an C# architecture example application. If I wanted to learn C#, I think I could learn a lot about application patterns from it. MVVM, how to separate the concerns into separate "packages" for reusability and the likes. What I can't really learn from it (without already being a C# pro, I work in other environments) is how to use the API.