I work on progressively larger and larger apps. This teaches me more and more about coding in the large, in a very practical sense. Every time I learn about something new, my learning is explicitly motivated by the problems that I ran into while implementing the large app.

I started by making a reasonably conplex TODO app, which took a few months. This taught me about the importance of declarative (popularized by React) style programming, and MVC separation.

Then I moved on to building a Vim extension for visual studio code. This took about 6 months, and taught me a bunch about programming larger apps and keeping them bug free. I also learned a lot about open source maintenance. I learned why Redux-style architectures are important.

Then I moved on to working on a fully featured pixel editor. This has been my toughest app of all. I've been working on it for about 4 months full time at this point, and I've learned so much about canvas perf, js perf, the importance of end to end testing, ... I could go on for a very long time. :)

And this is all a warmup for an even larger app I haven't started on...

This approach seems to have worked well for me, and I'd recommend a similar style approach of working your way up from smaller programs to larger apps. You learn lessons from smaller apps that will save you a lot of time when coding larger apps.