One character very likely has altered other characters' memories and/or psychologically manipulated them; however, this is briefly suggested or implied in Annihilation, and the fact that the character actually did that it only revealed in the sequels.
There is a scene where neither party appears to have given full and informed consent, although there is no explicitly stated non-consent, either: Two married characters have sex, but one party is apathetic and not communicative, and the other party is unaware that the person they are having sex with is not actually their spouse.
There are two primary examples of body horror; one character dies in the tunnels and has her body described, another time a fusion between a man and dolphin is described
There are massive amounts of body horror, but not dysmorphia in the sense of a distorted perception of ones own size/appearance or fixating on body image.