You may have noticed, but Apple never officially announces the RAM capacity of its iPhones. The brand probably believes that this figure is not of interest to the general public, even if the additional Ram is an essential assistant to the processor, particularly in terms of performance and multitasking.
The iPhone 15 Pro and iPhone 15 Pro Max have 8 GB of RAM
For the new iPhone 15, the macrumors site helped by programmer @aaronp613 discovered that the iPhone 15 Pro and Pro Max are the first Apple smartphones to benefit from 8 GB of Ram memory. For comparison, the four iPhone 14s as well as the iPhone 15 and 15 Plus are limited to 6 gigabytes.