Blurry grainy pictures with iPhone 15 pro max

My husband and I upgraded our phones a week ago from the iPhone 12 to the iPhone 15 Pro Max because of its camera capabilities. However, we are extremely disappointed as both cameras produce blurry and grainy pictures. We've tried adjusting all the camera settings and tips, but nothing seems to work. We upgraded our phones in preparation for our daughter's upcoming birthday, hoping to capture some great photos. I'm frustrated and have lost trust in the iPhone brand. Whenever we take pictures, the skin texture looks unnatural, almost like a hard surface. Surprisingly, my three-year-old iPhone 12 Pro still delivers better pictures with natural skin texture. Is there any way we can return these phones?"