Design patterns & Clean architecture in flutter

When I start programming a new application in flutter everything goes well at the beginning but when the project grows up it starts to become messy, and then I decide to delete the project to start over. I searched about the clean architecture and design patterns but I found a lot of choices such as DDD, BLoC, and so many patterns and architectures, I didn't what is the best thing to stick with every time I enter a research process that lasts forever. So I want to hear from you as professionals and expert coders what is the best thing to stick with and what should I do? please give some advice on how to deal with big projects in flutter? Thank you very much