I actually remember folding laundry and couldnt figure out why my mothers colors where stained so badly. Little did I know then about all the laws of niddah and how she probably just got her period and boom.
It was actually kind of gross.
Size of the underwear itself doesnt make a difference really kids know ppl are different so their clothes are bigger no different a shirt or underwear in terms of size
but in terms of privacy yes!