My cheap(ish) phone has ~30W charger too. It's something like 2,5A/12V or 1,5A/18V, which is pretty common these days. I believe I've seen phones with up to 100W charging capability (not sure about longevity though).
It looks like it'll only do 3A over 5V which is typical. You'll need to connect something that can accept 15 or 20V to get the full 45W. The upside of these is it supports 15V for devices that don't go higher, since it seems to be the least common supported voltage for usb pd chargers.