You can try HordeNG which has the ability to generate QR codes within a picture of your choosing. You can choose a resolution of 1024x1024 and a 4x upscaler which would bring the resolution to 4096x4096.

I don’t think all of that is possible with an account with no kudos (credits), but feel free to PM me, I can gift you an api key with some kudos to play around.