Can someone help me out how to get started in this kind of coding setup?

I haven't written production code for the last 8 years, but has prior development experience for about 17 years (ranging from C++, full stack, .NET, PHP and bunch of other stuff).

I used AI at personal level, and know the basics. Used Claude/Github to me help fix and write some pieces of the code in languages I wasn't familiar with. But it seems like people talking and deploying large real world projects in short-"er" amount of time. An old colleague of mine whom I trust mentioned his startup is developing code 3x faster than we used to develop software.

Is there resource that explains the current best practices (presumably it's all new)? Where do I even start?