As for iOS devices, Call of Duty: Mobile will be compatible on iPhones and iPads running iOS 9.0 or higher. This game will however not work on these iOS devices - iPhone 5s, iPhone 6, iPhone 6 Plus, iPad Air, iPad Mini 2, iPad Mini 3 and iPod Touch.
Call of Duty Mobile system requirements for iPhone: Requires iOS 9 or higher, or iPadOS 9 or higher. Call of Duty Mobile system requirements for Android: Requires Android 5 or later and your phone needs at least 2GB of RAM.