Is it possible to have butt cheek implants?

Yes. Yes, it is possible to have butt cheek implants. However, fat grafting to the buttocks is a safer and more effective procedure. It involves liposuction to remove excess fat from the waist, abdomen, or hips. Then it is cross layered into the upper buttocks to give them a more rounded, lifted appearance.
Yes. Buttuck augmentation can be done with your own fat or with implants. Be sure to visit a board certified plastic surgeon. Implants for this area are not breast implants and augmentation with things like free silicone are very dangerous to your health.