Dragons do not advance through training as humanoids do. They grow. As a dragon gains levels, its body develops alongside its experience, unlocking greater size, strength, speed, and destructive potential. These changes are represented by its Age Category.
Level/Age Category/Age Equivalent/Size/Bite Damage (Reach)/Claws Damage/AC/Speed/ Breath Weapon Size
1st/Hatchling/0 to 4 years/Small(5 by 5 ft)/1d6 piercing+1d4 energy (5 ft)/15/25 ft./
30 ft. line or 15 ft. cone
5th/Wyrmling/5 to 15 years/Medium(5 by 5 ft)/1d10 piercing+1d8 energy(5 ft)/1d6 slashing/
30 ft. line or 15 ft cone
11th/Young/16 to 100 years/Large(10 by 10 ft)/2d10 piercing+1d12 energy(10 ft)/2d6 slashing/
60 ft line or 30 ft cone