Yes.
My monitor puts itself to sleep to save power.
And cpufreq is set to conservative, but ondemand is fine too.
For openrc :
sudo pacman -Sy cpupower-openrc
(In principle you can configure '/etc/default/cpupower' but it doesn't work for me.)
Launch cpupower at startup:
sudo rc-update add cpupower
To occasionally modify the governor mode (example):
sudo cpupower frequency-set -g powersave
As I use XFCE4, I had the luxury of adding xfce4-cpufreq-plugin.
But the equivalent must exist for KDE.