Short and highly specific: Bezos’ API memo — https://konghq.com/blog/enterprise/api-mandate
An actual book that’s a bit broader but touches on system coupling/decoupling and is very practical for software people: Wiring the Winning Organization by Gene Kim
An excellent, very approachable primer on the overarching field of thought, which is systems theory, is Donella Meadows’ “Thinking in Systems”
Going back to more of the philosophical foundation (along with other valuable business ethics lessons), you should look into the work of W Edwards Deming and his “System of Profound Knowledge” — sounds pretentious but is EXTREMELY practical. This region of thought forms the basis of e.g. the Toyota Production System
And an absolutely excellent but more academic deep dive into precisely this topic of modularity is Carliss Baldwin’s “Design Rules.” It’s sort of a super-theory of Conway’s Law, but in a book-length argument.