Those things are tightly related but you mis-stated something there what you want to know is the ‘discharge’ rate not the ‘charge’ rate. The charge rate is always basically 1C if they don’t say otherwise which means you take the capacity of the battery in Ah and charge at that rate in Amps.
So if it’s a 5Ah battery for example (which I use) then it should be charged at 5A at max (will also depend on if your charger can put out that much current without overheating and shutting itself off).
Regarding the discharge rate if we assume it’s a 5Ah battery and 20C discharge rating (that’s max discharge, shouldn’t sustain having this much pulled from it) then you can safely pull up to 100A (5Ah x 20C = 100A) which I think is plenty. Say you have 5 2S in series or 2 5S in series it’s the same equivalent 10S so 37V nominal voltage * 100A = 3700W which is far more than the motor is rated to ever pull anyhow. You don’t need to do lipos in parallel if they are rated high enough, the higher the better though you will heat/stress them less and they will have less voltage dip under load (when amps are flowing).
Additionally the charge rate is important to be conscious of when it comes to setting your regen settings in the VESC so as to not dump too much charge too quickly back into the batteries, they can deal with more than 1C for a short period but don’t want to push them too much.
Sorry for the book… one last thing to add the C rating can be BS sometimes so looking for third party tests of internal resistance of the cells from different manufacturers compared to their claimed C rating is usually the best bet. Joshua Bardwell is an FPV geek I watch on Youtube who does some deep dive tests into different batteries/manufacturers and publishes his test data. Roughly speaking from what I’ve seen the C rating does correspond to max discharge but manufacturers may fluff the numbers some.