Charging a USB C device with fixed voltage / No Power Delivery/ Fixed dedicated Source
This laptop model only has USB-C PD charging option. PD has controller on each side of the connection (inside the charger and inside the laptop) and those two controllers will negotiate voltage/current. This negotiation is a must in PD connections.

Initial connection happens at standard USB 5V/max 0.5A, where devices then negotiate V/I increase in specific steps. PD protocol is rather complex and if you were to try to feed it permanent 20V DC it most likely will burn PD controller inside the laptop.

Just get any USB-C PD charger capable of minimum 65W (that is what you laptop rated at), and it should work.