What are some codebases from which beginners can learn to write good code?

Peter Norvig in his book "Paradigms of Artifical Intelligence Programming" says in the preface:

" All too often, the teaching of computer programming consists of explaining the syntax of the chosen language, showing the student a 10-line program, and then asking the student to write programs. In this book, we take the approach that the best way to learn to write is to read (and conversely, a good way to improve reading skills is to write). After the briefest of introductions to Lisp, we start right off with complex programs and ask the reader to understand and make small modifications to these programs.

The premise of this book is that you can only write something useful and inter- esting when you both understand what makes good writing and have something interesting to say."

Suppose a beginner who has taken an introductory programming or CS course using a language (for simplicity and generality say Python). Now they want to know how to solve variety of problems using that language and write good code.

What codebases should they read? What kind of projects should they start writing? By projects I don't always mean gluing together apis with minimal work to build an app. There should be significant work to do from scratch even if they use a few apis for some parts of the project.

Do you have something specific in mind for such understandable codebases or walkthrough blogs/videos?

For projects, I think in the starting there should be some handholding/guidance. Are there any such resource?