@Pavle . Let me be overly detailed considering what you have provided.
Android is software, just like Windows, Linux, or OSX.
Android runs on hardware that can vary quite significantly. (In this case, it's your S3 Neo)
It's safe to guess or assume that it has at least one voltage regulator (Buck and/or Boost) depending on the hardware.
I'll lead you through my thought process:
Does it have a battery? Yes.
Does it need to charge? Yes, then it probably has a buck converter or other voltage regulator for the charge circuit.
Does it need to output a higher voltage than the battery to anything? If the device has USB-OTG, then it needs to convert 3.7V to 5V... so it *must* have a boost converter in there somewhere.
What are the specs of this converter? No clue. This phone is custom tailored to a specific task for the least cost possible...
Can I use the boost converter for anything? Probably not. Boost converter relies on external components, and jurry rigging the phone's hardware to use it in place will probably break something.
I want to use the boost converter anyway. Fine. Look at the small part numbers on all of the chips on the board and google them. You may come across the chip responsible for the boost converter. The spec sheet you find in this step will tell you what it is capable of, and what parts are required to make it work hopefully.
But I can't find part number XXXX... Well... too bad, this phone has a lot of custom hardware in it. It's cheaper to custom make a chip and produce millions than it is to build a phone with a bunch more separate components. You won't find specs, and you will most likely never find a replacement chip unless you buy another S3 Neo.
Quick Summary:
It might, but it's not worth it to try to use, nor is it worth the time of anyone in a forum to try to find a schematic for a phone they will most likely never deal with again in their entire life.