It inverts the supply polarity, so you'll need to orient your project to be compatible.
Your control circuit will need to detect volt level to the load, and adjust duty cycle accordingly.
To show that the same components can provide 12V output, for a range of input between 5V and 20V, here is a screenshot of my simulation. (I made the control signal a simple clock, for ease of creating this layout.)
My diagram shows the same circuit as it would operate with a 5V supply (left) and a 20V supply (right).
It is a simplified demonstration to show that what you wish is possible.
It would need a mosfet or transistor as a switching device. It would need a control IC to apply the switching signal.
There are control IC's which detect the volt level at the load, and which alter the duty cycle of the switching device to maintain a desired volt level.
I have not used such IC's so I don't know specifically what to recommend.
Duty cycle(%) =\[\frac{Ton}{T}\] * 100
where Ton = On duration
T=Total period
i.e. in short, duty cycle is the ratio of duration for which the pulse is on(i.e. positive) to total time period which comprises of on duration + off duration.
So, for e.g. when u say 75% duty cycle, 75% of the total time period, the pulse is on.
Common software related to circuit designing are SPICE(u can use PSPICE, I think the student version is free, not sure check it out). Other one is Multisim.
Their tutorials are available on net, so u can start from scratch learning the softwares initially with some basic circuits then going to some practical circuits.