How much Micro SDcard size supports the nRF52840 DK
The QSPI peripheral on the nRF52840 uses 32-bit registers for specifying respective destination addresses and transfer lengths. This makes it possible to access a 4GB address space.
Can we connect a 32 GB micro SDcard with nRF52840 DK?
No, the limit is at 4GB. I'm not aware of a way around this unfortunately.