MVC with Riverpod

How can i implement MVC using Riverpod? and A class extending StateNotifier/ChangeNotifier will be a model or a controller?

2nd Question is: Should i design a specific feature first, and then refactor the code an and implement SOLID/Design Patterns ? Or I should design whole app and then refactor the code?
PS: I’m sorry, I’m just a beginner in Software Architecture.