Hierarchy is useful for reporting structures outside teams, but strict hierarchy within teams quickly approaches a land of diminishing returns.
No supervisor should have more than 8 people who need active supervision - you can have much larger teams than that, but it works out to a bunch of independently operating contributors and then "point people" who have responsibility for defined tasks. The number of point people is what is constrained by rule of 8.
I first came across this in the Marine Corps, which pushes you to ideally no more than 4 direct reports, with the idea that you could have up to 8 directly reporting temporarily, but that would lead to your own personal performance degrading in anything that's not directly managing those 8. Hence the structure would be 4 to a "fire team" with a team leader, 3 teams to a squad with a squad leader, three squads to a platoon with a platoon leader.
There's similar numbers found in the book An Elegant Puzzle: Systems of Engineering Management, and I want to say that similar numbers are espoused by Jocko Willink in his leadership books.
No supervisor should have more than 8 people who need active supervision - you can have much larger teams than that, but it works out to a bunch of independently operating contributors and then "point people" who have responsibility for defined tasks. The number of point people is what is constrained by rule of 8.