How can I write scalable code?

That is to say, how to make a good scalable program architecture at the beginning of a project? It can be expanded without limit after a few changes are made in the future. That is to say, how to make a good scalable program architecture at the beginning of a project? It can be expanded without limit after a few changes are made in the future.

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That is to say, how to make a good scalable program architecture at the beginning of a project? It can be expanded without limit after a few changes are made in the future.

Familiar with mature ideas such as design patterns, MVVM, and IoC.

Do not expand for expansion. Before design, analyze the requirements, which are the current ones, which are the future ones, and which do not need to be done. Designing a big and complete architecture is equivalent to having no architecture. The architecture should serve the project, rather than vice versa.
I have written several php frameworks before and even spent a lot of time on the frameworks. Now, okay, I don't need php anymore. Do php frameworks have any significance?

The open/closed principle is open to changes and extensions.

Abstract !!!!!