I think this article explains how to do it, and I think maybe the issue is that because it's considered to be a non-free repository, it's disabled by default.
Looks like you need to run sudo apt install software-properties-gtk and then open Software & Updates and in the Debian Software tab enable the 3 checkboxes below "Officially supported (main)" then you can run sudo apt update && sudo apt install nvidia-detect and nvidia-detect that will tell you which driver to install, although apparently according to this article it's usually just sudo apt install nvidia-driver.
The issue might also be that your system might have integrated graphics that Debian is apparently not very good at switching between like Ubuntu with the nvidia-prime graphics switching program. If that's the case, this article has instructions or you can look into envycontrol on Github.