There are no creams, potions, or supplements that will do what you are looking for.
The curve of the hip is caused by bone, muscle, and fat. The bone is not going to change. There are exercises you can do to develop your glutes and hip flexor muscles. That is the healthiest way. The unhealthy way is to gain weight and let the hormones move the fat to the hips.
I have heard of gals who do a combination of both. They cycle between periods of muscle-building/fasting and a period of stretching/feasting. The concept is that you would lose weight (fat) from all over the body while building the underlying muscle. Then use stretches to maintain muscle tone while allowing the fat to deposit on top.
I do not know if the method works or not. That is the concept. I gave up on curvy hips long ago. To help me, I spent time noticing women's hips. The ones who had curves were heavier women overall. The ones that had a decent figure had narrower hips, and some even had flat butts. That convinced me to be more realistic about my goals instead of chasing an image that I will never achieve.
I do have a set of hip pads that make one of my pairs of jeans look exceptionally good. But they are too hot to be comfortable for more than a couple of hours.
