The sentence "John is like a black sheep" is primarily connotative.
Denotation refers to the literal meaning of a word or phrase, while connotation involves the ideas, emotions, or associations that a word or phrase invokes. In this case, calling someone a "black sheep" suggests that John is seen as different or an outsider within a group (often a family or community), which carries a negative or rebellious connotation. The phrase evokes certain feelings and societal context rather than simply stating a factual description.