Facebook actually has no idea if Apple will ask customers to opt in on Apple apps. They are only guessing.
Most Apple apps that are built in aren’t on the app store, so they don’t have a nutrition label there. But there is a user agreement that comes with your phone, as well with each update.
But as far as opt-in or opt-out, you are asked about crash logs and analytics, can turn off just about anything, iCloud is NOT REQUIRED to use their products, and the app store doesn’t sell your info.