I've always read elves as very slight/petite. Obviously for live action films like LoTR you work with what you've got, which is why they're humans with pointy ears, and it obviously varies from setting to setting, but I've always read elves in DnD following the same sort of build as I read in Tolkien's work-think 'scrawny teenager' bodies. Heck, I think shadowheart's a bit to thicc, and she's 'just' a half-elf. This is ofc my personal opinion so don't expect poo to be flung if you disagree, lol.
