[Q] about flashing old firmware tarballs topic

So im wondering if im on nk4 firmware (bootloader and all), and flash the prev Ne5 firmware via odin (bootloader and all) i will definitely brick rule still applies, becuase im coming from a gs3, and that's how it was(becuase of knox and all), hopefully you guys know what I'm trying to say i don't know if knox changed but hopefully you guys can help me