The product can control up to two monitors simultaneously, either a single monitor at up to 8K or two monitors at up to 6K at 60 Hz. It has one DisplayPort 1.4 and two Thunderbolt 4 ports for monitors. The three USB-C ports are for data only and do not support monitor output.

As the three portable Dell P1424H monitors only have USB-C ports and the dock only offers two Thunderbolt 4 ports for monitors, not all three monitors can be operated simultaneously via the dock. A maximum of two monitors can be connected via the Thunderbolt 4 ports, the third monitor could not be recognised directly as a display.

To summarise: The dock supports a maximum of two external monitors at the same time, therefore three Dell P1424H Portable Monitors with only USB-C connection cannot be operated simultaneously via this dock.