You can do it manually if you are so inclined but never use Nvidia’s binary installer.
No reason to panic - but only use AUR if you are using Manjaro unstable branch.
nvidia-dkms is in the official repo - thus the driver will rebuild correct if you ensure you have the kernel-headers for the installed kernels.
If you have kernel-headers installed for e.g. linux61 then - using mhwd-kernel - installing linux66 will pull the headers automagically.