19 years old male with little beard. How could I grow a fuller beard?

Beard hair is a genetic trait similar to the color of your eyes and hair.  Some people are born with the genetics for no facial hair.

your age is very early to have  full beard on your face . You have to wait untill 22-23 , if you will still have that complain FUE  technique scalp hair to beard area transplant would be performed.

Many young men want to accelerate their beard growth and ask about it. It takes age (genetic triggers which occur in family lines) so if you want to find out when your beard will grow out, you need to find out when your father or grandfather started to grow their beard. Hormones should have kicked in nicely by the time a man reaches 18 but he must wait out his genetics as hormone alone are not responsible for the onset of beard grown. Beard transplants can be done when the young man is a bit older (over 25) if the beard has not grown in yet