She’s absolutely deluded, that does not fit her properly. The size 18 PJs buttons were straining and she also sneakily put the box in front of where she was standing so you couldn’t see her fully. She might be able to squeeze into smaller sizes but they don’t fit. And it doesn’t help that the clothes she wears are cheap and shoddy.
She is right that sizes vary but most of us who can squeeze into one or two items in the lower scale would not claim to actually be that size. See also Jess with her size 24 claims. They’re not bopo at all.