No explicit length requirements.
Should be more than the executive summary.
Include some backing information, preliminary analysis, and a discernible structure.
Policy options should be listed with pros and cons for each.
A specific policy should be chosen as the best.
Can be bullet points, but must be enough to convey your main arguments to a first-time reader.

I will attach the executive summary.

https://fas.org/sgp/crs/mideast/RL32048.pdf
This link might help you.