An excellent topic that you'll likely receive a lot of opinions about!
I use the Problem Solution How Execution framework as a high-level guide. I imagine you can back in some details to support a job description at each level.
- Junior PMs are handed the Problem, Solution, and How. They are tasked to Execute.
- In the second level of growth the PM is handed the Problem and Solution. The PM is tasked with defining the How and managing the Execution.
- In the third level of growth the PM is handed the Problem. The PM is tasked with providing the Solution while managing the How and Execution.
- At the most senior level (e.g. CPO), the PM is tasked with defining the Problem while managing the Solution, How, and Execution.