Drones power distribution
Typically the ESC draws power directly from the main supply battery. To do anything else would be a gross waste of power and payload.

Many ESC have built-in "battery-eliminators", i.e. a lower voltage output specifically designed to power the electronics (receiver, controller, etc.)

There are formulae for calculating track-width depending on current capacity and temperature rise.  Note also that PC boards are available with copper of different thickness.  High-current boards would seem more likely to use 2oz copper than the more common 1oz copper thickness.

Google for:  pcb trace width calculator