How can i get ariana grande(kat from victorious) body?

To get your butt bigger, then you should, yes be doing squats, since stronger butts are bigger butts. But papaya also helps (i think), and so does milk, although that also makes you over all fatter. For arms like that you should refrain from starving yourself too much and eating too much, I would suggest also working-out your arms, but not too much, if you make them too strong then they will look muscular (same with the legs). A good way to get a big strong butt and nice strong arms is dancing and/or yoga, dancer/dancing muscles don't look too muscular, and you get the same type from yoga. Good types of dancing for this are tap dancing, ballet dancing, and hip-hop dancing.