The full range of the current phones Apple sells today (2022 iPhone SE on the low end through the iPhone 13 Pro Max on the high end) both use the same chipset:

The full range of the current phones Apple sells today (2022 iPhone SE on the low end through the iPhone 13 Pro Max on the high end) both use the same chipset: the A15 "bionic". As you go up the scale, you're paying more for hardware features (better camera sensor, front depth sensor for face scanning, etc.). This will probably change pretty soon, only because the higher-end phones tend to be refreshed in the fall and the low-end phone was announced and then refreshed in the spring. Obviously, you can save some money by buying an older phone with better hardware features, but the same applies to Android -- this year's "mushy middle" of pricing is occupied with last year's flagship model.