What you're trying to test for drives the setup of the FG; not the other way around.
If I was testing a power amplifier to determine max. power output, I'd setup the FG for 1kHz sine, 10mVpp output initially, and 0V offset. My 'scope and MM (on ACV) would be monitoring the speaker terminals and I'd ramp up the output to a max. of 900mVpp (line level) as I check the waveform for any signs of clipping. Take note of the ACV reading (at just under clipping) to determine power (P=VAC^2/4ohm load).
My 'scope can do Bode plots automatically. Its built-in FG will ramp up the frequency from 10Hz to 20kHz, plotting amplitude and phase and give a nice graph. Of course this was once (and still can be) done manually with pen and paper. You decide, levels, frequency range, number of points, etc.
A typical FG can output 10Vpp, sine/square/triangle/ramp, +/-5V offset, 10Hz to 15MHz frequency and has a 50ohm output impedance. If your test need is beyond this, then you'll have to pick another signal source or, if you can, adapt the output to your need.