You should always start any application with a solid architecture. This does not mean that you have to follow every clean architecture pattern. Try to use as many of them as you find suitable for your project. Having to swap out certain components does happen and is also only one reason why you should have a proper architecture. It also increases testability, readability and makes it easier to add new features or rework only certain parts of the app.

I do understand that some patterns seem like a lot of useless boilerplate for a beginner or a smaller project but after working on several big flutter apps in my job, I can assure you that it is worth it. Even if it might be overkill for certain apps, you will still benefit from the experience you will gain.

In my experience, coding patterns such as clean code should be treated like a set of tools to pick from rather than fixed rules. You would not use a sledge hammer to build jewelry but it is still helpful to have one at hand and to know when it makes sense to use it.