As an example, what's beyond code quality is writing library code where doing the right thing is easier, and is aligned with the system. If, for example, one uses a design pattern whose anti-pattern is misaligned with the overall system, then it is easy to do the right thing locally and the wrong thing systemically.
As another example, the "best practices" are actually sound engineering principles applied specifically and locally. In a different architecture, with a different constraint and use-case, how those principles applied may sometimes look different than what "best practice" says, but not so strange if you understand the engineering principle underlying the "best practice".
Lastly, I would say, "systems thinking" always includes people: the people writing the code, the people making sure the infrastructure is running, the people using the system as end-users, the people supporting the users, the people running the business, the people paying the business, the people depending on the technology. Incorporating that means dipping into a product perspectives where people talk about things like, ux, or "job to be done", or "lived experience" rather than "requirements analysis" or "observability".
Systems thinking is broader in scope and responsibility. You're going to have to cross the rubicon eventually (unless all the software projects that hire you fail gloriously before they achieve any significant scale, I guess).
Code quality, best practices, etc. involve the same values and priorities as systems thinking, but is scaled down to a bus factor of 1. (i.e. the code you, personally, write or review).
Going beyond n=1 requires building mechanisms and guard-rails to prevent a failure of the individual level from affecting the larger system in a bad way. Thinking about it early won't significantly kneecap you from writing good code.
If it interests you, go for it.
The only reason you might not want to do so is if it doesn't interest you right now. You'll likely get there one day, once a project you care about scales up enough.