A few comments on this: nvidia-settings is available but it seems to be misconfigured. In my case, I have to use nvidia-long-lived 390.87 and nvidia-settings is found in
/usr/lib64/nvidia-long-lived/bin/nvidia-settings
But, nvidia-settings itself looks for libraries at
/usr/lib64/nvidia-current
It seems there’s a kind of misconfiguring of OM LX 3.03 nvidia 390.87 package.
Then, to be able to launch nvidia-settings one must do
/usr/lib64/nvidia-long-lived/bin/nvidia-settings -I /usr/lib64/nvidia-long-lived
Anyway, it seems that the nvidia-settings I get this way does not have all the options it seems to have at