I’ve posted this before, but with the incorrect link, and it got buried in another thread anyway.
For each of the BB tests’ essays prompts there are given 6 sample essays - one per score from 1 to 6 (well, you don’t need those 1-3s) - with the scores explanations:
https://sat.collegeboard.org/practice/sat-study-guide-owners-area?excmpid=CBP6-ST-2-guide