It seems like the important metric would be the kettle's power output, not the voltage. A kettle running at a lower voltage can still have the same power output (wattage).
My kettle is 1.5kW. I'd be surprised if consumer kettles ran much higher than that.
EDIT: TIL about 3kW European kettles and what I'm missing out on.
Here in the UK, my kettle's a 3kW one (with limited temperature control) and most domestic ones will be over 2kW. By my quick calculations, it runs as 12.5A on the usual 240v supply. To get a 3kW on 110v would draw over 27A which would likely be impractical for a standard kitchen appliance.
My kettle is 1.5kW. I'd be surprised if consumer kettles ran much higher than that.
EDIT: TIL about 3kW European kettles and what I'm missing out on.