DE10 Lite FPGA internal RAM usage

No. .sof is for direct programming of the FPGA through JTAG. It’s not stored anywhere other than the computer you’re using to program the device. .pof can be stored in a flash (non-volatile) memory so the FPGA is configured automatically on power up. An SDRAM cannot store programming information because it is volatile, and the FPGA cannot access SDRAM until it is programmed because the programming sets up the controller and PHY needed to communicate with the external memory. So your questions don’t make sense. I’d recommend reading the programming/configuration chapter of your targeted device family for basic understanding of how FPGAs are configured and used.