Alternative to skill, you can solve this problem with money.
USB-C “trigger cables” that have the hardware to request a voltage from the supply and a barrel jack on the other end are common enough, and available in most of the standard voltages: https://www.adafruit.com/product/5450
For more money, you can have ones that support PPS mode (3.3 - 48V in 0.1V steps) from a compatible supply, and a dozen interchangeable cables (including centre negative): https://werewolf.us/collections/werewolf-products
As someone in another thread pointed out, The Onion already called that one…
https://theonion.com/nation-could-have-sworn-russell-brand-was-already-convi-1850849838/