Question about fpga

If I understand you question correctly, that answer is yes, with conditions:

If the FPGA is large enough you can just build the design with all 4 functions in it, with a master mux that controls which one is active.

If it's not large enough for all 4 functions, it's possible to re-configure the fpga fabric on the fly, but I haven't had to do this yet, so I'm not sure exactly what's involved.

If there's an outside CPU that is controlling everything, it could just load the FPGA itself with the appropriate bitfile, for the function that was required at the time.

Pete