Like its siblings, this 4K display has some control hardware tucked away behind the front panel:

Texas Instruments TPS65168 High Resolution, Fully Programmable LCD Bias

Texas Instruments TPS54320 4.5 V to 17 V Input, 3 A Synchronous Step-Down SWIFT Converter

Texas Instruments TPS54218 4.5 V to 17 V Input, 3 A Synchronous Step-Down SWIFT Converter

Parade Technologies DP665 LCD Timing Controller (the same found in last generation's 27" 5K model)

We assume this is an Apple modified version of the DP663

Texas Instruments NH245 55K G4

Texas Instruments BUF16821 Programmable Gamma-Voltage Generator and Vcom Calibrator