They are some sort of boss in easy dungeons in mobile ARK (I don't know about the other difficulty), it's hard to tame them with carrots (that's what you need to do to finish the dungeon raid) because you cannot feed them with carrots and I just re-read the dododex and a person mention that it could not be tamed in mobile with carrots, so I recommend kill the unicorn 😶. (I hope it's useful)

Killlllllllllllllll!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!