If you’re making your own battery pack you could use something like this - https://m.ebay.com/itm/12-24V-to-QC3-0-2-0-DC-DC-Step-Down-Buck-Converter-Charging-Circuit-Module-6-32V/163197438071?hash=item25ff534877%3Ag%3Aw0UAAOSw-95bbxZF&\_nkw=qc2+charge+circuit&\_from=R40&rt=nc

I have one connected to a 3s lipo for qc2 charging my phone