Designing a high voltage AC signal generator
It may work between 50 Hz and 400 Hz. Over that range your transformer will avoid saturation. If you want it to work down to 1 Hz, you will need to apply a maximum of only 1/50th of your transformer rated voltage to each winding, and can expect to get only 1/50th of the rated voltage out of any winding. A minimum frequency of 10 Hz will mean you must apply no more than 1/5th of the rated voltage, and so on.
A low cost mains transformer may struggle with loss at 400 Hz. You can get transformers rated for 400 Hz, but they cost more due to the thinner laminations.
You can get power audio transformers, which will have the right sort of voltage ratings if they're designed to be driven by valves and drive a low impedance loudspeaker. Again the low frequency response will be limited.