It looks like the answer is “Yes”:
“To ensure consistency between bikes, Zwift Hub One is able to detect the gear ratios on your physical bike which allows it to set the virtual gears accordingly,” says Zwift. “It achieves this through a process called ‘real gear ratio calibration’. The trainer does this within the first few seconds of every ride automatically. Magic.”
In fact, Hub One calculates the real chainring size of the bike mounted on Hub from cadence and flywheel speed, and then auto-calibrates resistance.
Zwift says, “In addition to delivering benefits to those with multiple bikes, real gear ratio calibration offers new benefits to riders using smaller chainrings, like those found on gravel and mountain bikes, preventing those riders from spinning out on flat or downhill terrain in Zwift.