Fitting a USB C plug onto an laptop power adapter
I can charge my phone at 9V run a Raspberry pi at 5V  or charge my laptop at 20V all using the same USB C power brick.
USB3.1 power delivery is very complicated it needs a special circuit in the charger that negotiates the voltage, and the powered device needs to ready itself too.
there are power delivery modules available. connecting one of them to your laptop charger may work