Where it is: Settings → Pricing & Limits — maximum answer length and answer depth.
Left alone, language models write essays. The plugin calibrates length to the question: a yes/no question gets a sentence, a “how does X work” question gets a short structured answer.
You can influence this with the response-length setting and with your persona. What you should not do is ask for long answers in the persona field — it applies to every reply, including “are you open on Sunday?”.