Audio Upgrades

Hello .
I currently own a Prius C 2019 , the facelift version . From the dealership it had a generic head Unit since then I have upgraded it to a pioneer AVH G225bt and added an amp (pioneer Gm 9604) powering a single sub(ts w311s4). For the time being my speaker are running off the Head unit itself; but later I wish to add a second Amp for the speakers(Mid and tweeters) so as to better manage my audio routing for better quality a higher volumes and not to overload the amp.

My question : Can I change the 12V for a bigger one? Can I add a secondary 12V battery ? Since the car is uses electricity to run all its system I don't want to drain or overload the 12V battery or create any disruption .

I'm not an electronic/electric expert , I'm just asking question about the possibilities and whether or not it's possible. I'm aware that the car doesn't have an alternator.