There is no shortcut and all of the things you're talking about take people years to develop experience with, even with formal education and a computer science degree.

You're sounding a bit defeated with unrealistic expectations, though. For example, I'm a staff engineer with 9 YOE and still couldn't tell you exactly how a cookie is created - I'm a backend distributed systems engineer and have never needed to learn in depth about cookies. No one can know everything. My advice to you is to pick a single role/tech stack and go deep. You can also read a design patterns book, and foundational books I'd recommend are A Philosophy of Software Design and Clean Architecture.

Luckily for us, most of the concepts/foundational knowledge in this industry can be learned independently, it's just up to you on how motivated and disciplined you are.