As soon as the iPhone 12/12 Pro were released, IFIXIT did a live video of the teardown to see which chips and components made it into the US version phone. I will review below the RF modules that were identified in the teardown. Qualcomm and Skyworks had the bulk of the RF modules so stand to gain the most from iPhone 12/12 Pro sales. In the below photo, the yellow rectangle is a Qualcomm SDR865 5G and LTE transceiver, the green is a Qualcomm SDX55M 5G modem-RF system and SMR526 intermediate frequency IC and the dark blue is an Avago 8200 high/mid power amplifier with integrated duplexer.

The next photo below shows the Qualcomm SMR526 RF transceiver in orange, Qualcomm PMX55 power management in green and the Skyworks Sky5 RF modules in blue (8 of them!). The 8 Skyworks modules might be different ones but are still being identified.

The US models come with 5G mmWave antenna modules—one embedded in the side of the frame, and another on the back of the logic board. The antenna module is in the frame is a USI product, labeled 339M00104 S30U7FH. It looks like a Qualcomm mmWave module but no is sure yet if it was made by USI or just assembled at USI from Qualcomm mmWave modules as they are the only known manufacturer of these types of modules.

IFIXIT has a complete video and photos identifying all of the chips and modules in the iPhone 12/12 Pro which you can find here. All images and identification information came from their analysis.