Not sure if this works on a PW2, but you can customize font-size on a Kindle Voyage that has 5.6.1.0.5 or higher (including 5.6.2.1) with a simple hack that involves copying a text file with 8 numbers into the Kindle's root directory. No jailbreak required. More details here:
https://www.mobileread.com/forums/sho...12#post3088512