So how do I design a power detector and what should I simulate to design it?
I thought that the most important specs are DR and sensitivity.
I have already told you but you didn't read my suggestions.
Define a low voltage limit and high voltage limit and vary the Input Power.
When lowest or highest limit start to shrink so no meaningful changes in voltage limits (in other words compression at limit levels.) these point are your highest and lowest RF limits.
And the range between these two limits is dynamic range. But measurements will give you the exact dynamic range and error.