While Redcore Linux defaults to the open source x11-drivers/nouveau, it does provide two versions of the proprietary graphics driver for NVIDIA graphic cards : x11-drivers/nvidia-drivers && x11-drivers/nvidia-drivers-legacy. Depending on the age of your card, you can install one or the other, as they cannot coexist on the same system.
The x11-drivers/nvidia-drivers package supports the most recent cards, and it should be your first choice if you have such a card. A list with the supported cards can be found at https://www.nvidia.co.uk/Download/driverResults.aspx/175958/en-uk.
Using sisyphus (cli):
root # sisyphus install --ebuild nvidia-drivers These are the binary packages that would be merged, in order: x11-libs/gdk-pixbuf-xlib-2.40.2 Total: 1 binary package(s) These are the source packages that would be merged, in order: acct-group/video-0-r1 sys-kernel/nvidia-drivers-dkms-460.67 x11-misc/nvidia-settings-460.67 x11-drivers/nvidia-drivers-460.67 Total: 4 source package(s) Would you like to proceed? [y/N]
root # emerge -av nvidia-drivers These are the packages that would be merged, in order: Calculating dependencies ... done! [ebuild N ] acct-group/video-0-r1::gentoo 0 KiB [ebuild N ] sys-kernel/nvidia-drivers-dkms-460.67::redcore 173,528 KiB [ebuild N ] x11-libs/gdk-pixbuf-xlib-2.40.2::gentoo USE="-gtk-doc" ABI_X86="32 (64) (-x32)" 53 KiB [ebuild N ] x11-misc/nvidia-settings-460.67::redcore 1,205 KiB [ebuild N ] x11-drivers/nvidia-drivers-460.67::redcore USE="X acpi dkms (libglvnd) multilib tools wayland -compat" ABI_X86="32 (64) (-x32)" 0 KiB Total: 5 packages (5 new), Size of downloads: 174,784 KiB Would you like to merge these packages? [Yes/No]
The installation process takes care of everything, so no further action is required. All you need is reboot the system.