After searching, I haven’t found much information on the scoring of the optional essay section on the new SAT besides what is detailed on this page: https://collegereadiness.collegeboard.org/sat/scores/understanding-scores/essay
So I have a few questions:
What is considered a good score, and what is an excellent score (like to get into Ivy League schools)? What percentile of people get a perfect 24/24? How much do schools (in particular the UCs) care about the essay section?
There is no data yet regarding the scores received on the essay portion and acceptance rates.
However, while there may be some correlation between those scores and acceptance, it is unlikely to be a causal factor. The essays are not being scored reliably or well, and many schools have opted out of considering the essay section entirely. Check the admissions requirements of your particular target school to see whether they ask for the essay section, but I wouldn’t fret much about the actual score.