"Transformers actually don't have an intrinsic voltage."
Transformers do have an upper limit on voltage, depending on the line frequency as well. The limiting factor is the point when the core starts saturating. When that happens, the core acts like it's not there anymore, the inductance drops low, and current from the line soars. Not a good thing. Thus a transformer meant for 120V 60Hz will burn up if fed by 240V.
Back in olden days, there were a few areas served by 25Hz, and power transformers in consumer equipment had to be much bigger. You needed about 2.4 times the number of turns for the primary, given the same size core. Or a bigger core. But as the line frequency goes higher, that 25Hz transformer could operate at twice the voltage at 60Hz (assuming the internal insulation can take having all the secondaries running at twice their original voltages).
I have some radios from Australia (which is a 240V 50Hz country) whose power transformers are quite happy running off 240V 60Hz in the USA.
