Dragon Kings (I'm not affiliated with DTRPG in any way) has the details for turning into a dragon on Athas.

You must be a 20th level psionicist and a 20th level defiler (wizard that damages the environment with every spell they cast) to become a dragon, and you slowly transform from a human/half-elf at 20th level to a full, 40-foot long scaled and winged beast with yes, a sand-blasting breath weapon at 30th level.

Starting at 21st level you can cast 10th level psionic enchantments (OK, technically at 20th level you can cast Dragon Metamorphosis). And each time you cast one of those, you drain life from animals as well as plants. You get various features of the dragon at various levels (wings, flight, breath weapon), and your AC improves and you gain about 60 extra 4-sided HD, magic resistance, and immunity to non-magical weapons.