If you want to be more niche and are doing for example phone charges for iPhones then you can look at using the target preference for people who use iPhone 8, X, XS Max etc. Another option to try is only targeting to iPhone users and no android users IF the product you are selling is for that market Just play around with targeting - Facebook is an amazing platform if used for its potential, but it won’t work if you give it no logical targeting. Best of luck!