You normally only need to install Nvidia. After that you can install Optimus if you want to use Intel only, hybrid or Nvidia.
The way it works is that without any Nvidia driver your computer will only use the Intel graphics. If you try to connect an external monitor it commonly does not work, until you install Nvidia driver, then it will activate that GPU.
If you want to activate Nvidia on the laptop screen, you use Optimus to switch the card, which will log you out and back in.
If you have enough with that nonsense, as alternative you could switch off the Intel altogether and only run on discrete Nvidia GPU. You can normally do this in the bios setting under display. But need to blacklist Intel at boot in grub so it uses only Nvidia. Beware more battery drain and you can run into driver problems on update, making potentially boot to black screen. The easiest is to go back to bios, tenable hybrid and go troubleshoot driver. Alternatively you could try and fix things from cli.