I’m quit a novice my self,but followed a few instructions and managed to make it work.
(when i first installed manjaro,i chose boot with propriety drivers which i guess made it easier)
i should mention there has just been a major update that also concerns nvidia drivers support etc.so i have no idea how this affects you and for my part,i guess I’m about to find out .
so check if yours is supported.
this is the official github page:
manjaro wiki page
https://wiki.manjaro.org/index.php/Optimus_Manager
and some more stuff to read for more details and later configurations:
https://archived.forum.manjaro.org/t/guide-install-and-configure-optimus-manager-for-hybrid-gpu-setups-intel-nvidia/92196
that’s in-case you installed the OS with Free drivers: