How does that work? Fat injection or silicone?
I don't know, your guess is as good as mine. Fat, silicon, implants, pmma, etc.
I saw this vid on YouTube where these Armenian women in the US who looked a lot like Kim Kardashian were getting their butts done, to be more shapely. It showed the process and what they were doing, adding more "padding", creating more anal cleft, etc.
The thing is with American women, they get the asses but don't work out the legs to balance it out. The Brazilian women work out the hams and quads, so to not have that skinny legs large ass look like Kim does.