Jesus uses a question to make the people think about what kind of man John the Baptist is. Alternate translation: "But surely you went out to the desert to see a prophet!" (See: [[rc://en/ta/man/translate/figs-rquestion]])
This can be translated as a complete sentence. Alternate translation: "he is not an ordinary prophet" or "he is more important than a normal prophet" (See: [[rc://en/ta/man/translate/figs-ellipsis]])