It is already pretty “modular” in the sense that you can get either the larger or smaller battery and easily swap them out.
Having an XL battery like you said is mostly a weight consideration but certainly doable. On trikes like we did here we’ve flown with 2 batteries in parallel. If/when we have the time to focus on trikes we’ll likely build off of that concept.
I think what you’re getting at is, could you do an equivalent to what ICE offers today where if you can tailor your exact amount of gasoline to your flight and have more fuel & weight for longer flight time and vice versa depending on the day? Because of the overhead of battery management systems, cells with different voltages and discharge rates etc, unfortunately electric will never be quite as flexible. Could you get close and do something like electric lawn mowers do to use a number of tool batteries? (see below pic) Sure, but you’d be sacrificing a lot in weight, and complexity aka. cost overhead to handle more than a couple battery packs.
