Apple was always little shady about revealing real amount of RAM in iOS devices – there are no official data. First iOS device with 4 GB of RAM was an iPad Pro from 2015 and most iPad Pro models got 4 GB of RAM. iPhones do not need such amount of RAM as iPads Pro, but current lineup is on par with current iPads Pro from 2018 and 2020. iPhone 12 and iPhone 12 Mini are equipped with 4 GB of RAM and their Pro counterpart got 6 GB of RAM.
In the Xcode 12.1 beta, as reported by server MacRumors, are .plist files which contain data about RAM amount. These files accurately revealed RAM amount in several generations of iPhones. iPad Air 4 got 6 GB of RAM. A14 Bionic SoC in iPhones 12 are relatively on par with single-core performance in iPad Air 4, but in multi-core benchmarks, iPad Air 4 is significantly faster.
What about new upcoming iPads Pro? How many RAM will they get and how fast will be A14X in compare to A12 in iPhones 12 (Pro) and iPads Air 4? I hope these new monsters from Apple will get at least 8 GB of RAM. New iPads Pro should be introduced in the Spring next year, probably on March 2021 event.