How to confifugre amount of SPIFFs vs OTA, etc

[davepl]

On at least one ESP32 board I've seen options in the Arduino IDE for changing the size of how the memory map is laid out - how much is reserved for SPIFFs storage vs OTA copies, and so on. It allowed you to, for example, lose OTA but have a much bigger initial flash.

I have two questions:

1) How do I configure these on a board like the Heltec WIFI Kit32 board?

2) Is there any difference in the amount of heap and program memory possible, or just flash sizes?