Yes, they can! When you are growing up, your bones grow with you. The cartilage (rubber-like padding that covers and protects the ends of long bones at the joints) grows first and then slowly gets replaced by bone with the help of calcium and phosphate salts. This is why it’s important for children to get plenty of calcium when they’re growing up. The process of replacing cartilage with bone is called ossification.
To expand on what Katie mentioned, Bones start as cartilage and then slowly get replaced by bone with help from calcium and phosphate salts, if you are deficient in Vit D ( which is the vitamin we get from Sunlight ) then your bones can actually remain soft and rubber like which leads to deformed legs, this is called Rickets. It used to be a huge problem in the industrial era due to all the smog coming from all the factories!