With this data, Graphic card is Optimus?
~$ lspci -nn | egrep -i "3d|display|vga" 00:16.3 Serial controller : Intel Corporation 6 Series/C200 Series Chipset Family KT Controller [8086:1c3d] (rev 04) 01:00.0 VGA compatible controller : NVIDIA Corporation GK208 [GeForce GT 720] [10de:1288] (rev a1)
If this is Optimus, which one is better?
Using PRIME Render Offload - Theoretically, with Debian 11 (or newer), special configuration shouldn't be needed and offloading should be available as soon as you've installed the proprietary drivers. See the relevant section for more details.
Using only the integrated GPU - Uses little battery power but is also low performance, as the NVIDIA GPU will be completely powered off. Still, this is suitable for some use-cases.
Using only the NVIDIA GPU - High performance but is also a massive drain on battery life. There's almost always a better solution than this, but it's useful if you expect to use your laptop as a desktop (i.e. always plugged in).
Using Bumblebee/Primus - An alternative solution to PRIME Render Offload that works similarly, with support for both Nouveau and the proprietary drivers. Up to Debian 11, this has had severe performance issues for some. While the situation is much better in Debian 11, this should really only be used if the official PRIME Render Offload functionality in the proprietary drivers does not work for you.
Using nvidia-xrun - Runs a completely separate desktop session with the NVIDIA card, achieving maximum performance from the GPU at the cost of extra complexity.
Using Nouveau - Nouveau is the open-source driver for NVIDIA GPUs. It also supports PRIME Render Offload via Mesa without the need to use the proprietary drivers. Unfortunately, it does not support Vulkan and has severe performance issues, particularly with modern cards.