Apple's upcoming smartphones are still equipped with the same amount of memory that was already built into the respective iPhone 12 predecessors. In comparison with its Android competitors, Apple is still lagging behind when it comes to how much RAM it puts into its flagship devices.
https://www.notebookcheck.net/Apple-s-iPhone-13-iPhone-13-mini-have-4GB-of-RAM-while-iPhone-13-Pro-iPhone-13-Pro-Max-come-with-6GB-of-memory.561893.0.html