vous avez une grosse tête
you could say cabezon (emphasizing on the O, i cant put an accent mark :[ ) or cabeza grande.
Nu'i po'o
You have a big head : rasaak kbeeer ( In Arabic ) if you want to say that for a boy for a girl you say : rasik kbeeer ( in Arabic ) it is written this way : راسك كبير
Elle a une grosse tête. (considering the size of the head) Elle a la grosse tête can mean - she is pretentious