After a certain threshold of complexity and size any software becomes a collection of trade offs and compromises, never something you might call a “clean architecture”. Its a red herring, myth, utopia.
It’s a thousand years old attempt to calculate and reduce the complexity of real world interactions and problems to a bunch of mathematically elegant metaphors and formulas.
The threshold is usually very low - first bunch of real world paying customers, real world usecases, startup market fit etc.