Not possible in 6 months unless she took 6 months off of lifting and lost a lot of size or unless she got fat and puts weight mainly in her thighs and legs
Probably a combo of diet/exercise/injections etc. All of it.
Women that lift/eat healthy...especially white broads, will get some thickness on the booty but it looks more "solid". Her booty is really jiggly. Squats give you thick, sprinter booty like Shelly-Ann from the Jamaican track squad.
Stomach stays flat, booty gets hella big and jiggly but not high/solid but she worked out? That's like a 5'9" 300 lb breh with an 8-pack. Need some pharmaceutical assistance for that shyt.