Rarely. Xiaomi does not release CAD files publicly. However, some reverse-engineered .brd files exist for the motherboard layer 1 and 2 on Russian 4PDA forums. Use software to open these.
Like many modern Xiaomi devices, the POCO X3 uses a mainboard (logic board) and a sub-board (daughterboard). poco x3 schematic diagram download
If you're using these schematics for hardware identification, here are the key components for each model: Poco X3 Pro Snapdragon 732G Snapdragon 860 PM7150 + PM7150L Surya / Karna Vayu / Bhima Important Note Rarely
No backlight? Trace the and LED_CATHODE lines to the boost IC. poco x3 schematic diagram download