Thank you for the advice. The ceiling is vaulted, and I have tried both raising and lowering it. I must be missing something very basic, since the ceiling and roof are not behaving like I expected. I am not sure what is controlling the roof height.
Here is a 120" ceiling structure and the elevation, and the walls still show
followed by a 72" ceiling and elevation, and the walls disappear, but the porch beams/soffits are still the same:
For the 6ft structure, the walls have disappeared, but the porch ceiling is much higher than 6'. It does not change even at 120"