Elves were suppossed to be perfectly beautiful as per myth, yes, they were alien and weird to us, but that's because we're uglier and more connected to earth itself rather than living nature. In fact, myth elves would be considerable OP when compared with their more modern fantasy counterparts, being already MADE as warriors, wizards, sages and artisans, with a strong connection to living things and the gods.
Since mammaries have a function as a natural sign to mark females as sexually mature and able to bear offspring, while allowing males to interact with them face to face (remember elves are more civilized than us in those aspects, they enjoy poetry, arts and the like), its not inconceivable that the female elven physique would be tall, slim and muscular, with less fat than the human female, but every ounce of it just primed to signal the male "hey, maybe you can start your decades long courtship right now to fertilize my eggs ASAP before we go extinct because humans reproduce way too fast"; meaning that by difference, they seem tittier than other females of the setting (probably like how the shorter races seem also more developed because of proportions). Therefore it makes sense that every elf (moreso in ages dominated by humans, half elves and elven blooded human groups; when the race is declining) is a superbabe. To normal humans she'd have a fascination effect like a lesser nymph would (another being that should be considered alien AND beautiful at the same time, not just pretty pinup girl). And if you ever see one that looks kind of old and has sagging breasts or wrinkles for the love of your gods do not piss her off, she's probably a supercaster.