Do I need EOS, OKRs or some operating system for my agency?

Everyone raves about EOS/Traction but I don't know if it's right for us

An operating system helps if your problem is lack of rhythm, clear ownership and accountability, which it often is at this size. But the system is a vehicle for the disciplines, clear goals, owned numbers, regular cadence, honest meetings, not magic in itself.

Adopt the disciplines first; the named framework is just one way to package them.