Build a clean asp.net core applicatio need consider a lot of things, like coding, architectures, High performance and scalability requirements and so on.
To learn how to build a modern asp.net core application, I suggest you could read this e-book. This e-book contains a lot of information to help you develop a good asp.net core application.
ASP.NET Core architecture e-book
Also it contains an example project which has updated to asp.net core 7. This is the link.
If the answer is the right solution, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.