A Pi will not 'negotiate' how much current it gets from any source. It draws what it needs, from what is available.
If you use a USB-C cable with an appropriate Micro USB-B adaptor, you will get 5v @ whatever amperage the power source (and cables) is capable of. If your power source is a "smart" USB charger, then the Pi will only see the "slow charge" setting.
Using USB-C to get more current is silly and not going to do what you think.
User experiencing technical difficulties.