Lux support confirmed that their Konoz zigbee thermostat supports Auto changeover, but that it must be configured by the controlling software, i.e. the Hubitat driver in this case.
By default no "Auto" option appeared so I tried to apply the steps mentioned in this thread: Thermostat scheduler unable to set fan or mode - #27 by bravenel
But despite supportedThermostatModes showing as including "auto" as a value, "Auto" still doesn't appear in the "Set Thermostat Mode" ENUM.
Would fixing this require Hubitat to update the built-in LUX Zigbee Thermostat driver? I'm not proficient enough to attempt creating a custom driver, and it's not clear to me if something like "Generic Zigbee Thermostat" could be used instead.