The chapters are independent from one another. But if you’re new to iOS development in general, you should read the book from cover to cover. The first two chapters explain in detail what to do and why to do it that way, and the last two chapters assume you’ve read or already understand those explanations.
As I mentioned, throughout the book we use storyboards, code, and SwiftUI to create the user interfaces for the apps. When you have finished the book you can increase your skills and maximize your learning by recreating the projects using a different approach for the user interface. Or you can even build an app that combines two or three of the projects. Invent something new.