While Super Mario 64 DS (2004) did not natively support QR codes, the modern "QR code" phenomenon associated with it refers to the , specifically for the Nintendo 3DS.
You can play the original DS cartridge on any 3DS system. While you can't "scan" the game into existence, you can use the for slightly smoother movement than the original D-pad allowed. The "Wario" Unlock super mario 64 ds qr code
Since QR codes didn't exist in 2004, here is the legitimate way to unlock the content most people search for when looking for "SM64DS QR Codes." homebrew and modding communities While Super Mario 64