Digging a little deeper, we find the RF board (XS on left, XS Max on right):

Apple/USI 339S00551 (XS) and 338S00540 (XS Max) WiFi/Bluetooth SoC

Intel PMB9955 (likely XMM7560) baseband processor/modems

Sorry, Qualcomm fans.

ST Microelectronics ST33G1M2 32 bit MCU with ARM SecurCore SC300

This is the same embedded SIM (eSIM) that we found in the Apple Watch Series 3 and the Google Pixel 2 XL.

NXP 100VB27 (SN100V) NFC controller

Broadcom BCM59355A wireless charging module