I’ve read in Kaplan’s book that an essay is not about content, so are good examples from personal experience less relevant than those from history or literature?
In my opinion, it sort of is, sort of isn’t.
SAT graders are not going to fact-check your essay, so you could probably get away with saying that P = NP was proven or some other BS claim (although saying that flying cars existed in the 1600s might raise an eyebrow).
I tend to prefer examples from research or history (including current events), followed by examples from literature, followed by personal experience when writing any argumentative essay, including the SAT.