Do some bra stores( Aerie or Victoria Secret's) do vanity sizing for their bras?

i'm not just talking about those places either. anyways, at those two places i can fit into a 34C, but i don't look like that. i look like a 34C when i'm wearing a push-up bra from one of those places. if anything, i'm a plump 34B. so do they do Vanity sizing?