If u have a small face and a small head, will it grow?

Yes. Yes by reconstructive surgery, consult a plastic surgeon , or oral surgeon who does these procedures by your twenties you reach your adulthood bones stop growing. Cost you have to find out from the surgeon, some times insurance covers.
Depends. At a listed age of 41, if you are asking for yourself you are done. About 90% of adult head size is reached by age 9 and sutures close preventing further growth before middle age.There is a proportion of the population that will have heads/faces on the smaller or larger size, based on genetic input.Skull and facial abnormalities noted in infants may require reconstruction by a craniofacial center.