Is this polygon pour, how much current can it carry?
If your pour is wider than the trace you'd need to use to achieve your desired maximum resistance, then the polygon itself will not be what limits your current.

If you really want to know the effect of the polygon geometry, you can do a finite element analysis to find the resistance of the important paths.

In terms of the overall design, don't forget to also consider:


Via resistance
Return path resistance
Inductive effects (in case you need to switch the current on and off quickly)