Hi Liam. Adafruit make a 5V only version: MPM3610 5V Buck Converter Breakout - 21V In 5V Out at 1.2A : ID 4739 : Adafruit Industries, Unique & fun DIY electronics and kits
and they also make a 3.3v variant.
I used a generic unit from ebay that supports a bunch of fixed voltage outputs as well as an adjustable one: See:https://www.ebay.com.au/itm/392619758057?var=664563194959
