Hello everyone!!

I have couple of doubts regarding process of software development and LLD.

In my college, they taught me about BR, Usecases and Worflows. And for interview preparation I learned LLD.

Today I was making an android app. Before coding I was planning to make BR, usecases and workflows. and also LLD diagrams so that I can add new features easily in feature. But I don't know how to replicate these things in the code. Like in android I am following MVVM architecture, I don't know in which file I should write BR, workflows.

I was wondering that companies like Google, meta etc do this things??

And also I am very confused about LLD part. While I was studying LLD there was a problem statement "Design Riding app". I made classes and defined relation between them. But I don't know how to take help of that design while writing the code. In LLD there is no frontend or backend. Every thing is mixed. And while developing application there is frontend and backend. I think you got what i am trying to say.

I want to know how to make maintainable and scalable code(in terms of adding new features).

Thanks in advance!!