There are no child clothes in her size, well THERE MIGHT BE but they're designed to have the opposite effect.
That is a good point. My great aunt had to buy clothes from children's department...at the age of 95 (short and small). And I had to buy from adult's department... at the age of 10 (I was tall).
I remember a Gawr Gura stream where she was talking about having to buy child clothes (or at least child sized) because she's also very small irl. Additional note how airport staff assumed she was a child lmao
I know Kobo from HoloID has been noted as very tiny irl by other ID members, I remember once she posted her weight that was really low. It's been a minute so I don't remember but maybe 80 pounds or so?