demm On a spare laptop, I installed Manjaro KDE Minimal and I had to manually install power-profiles-daemon package to enable the power profiles. On Kubuntu and Endeavour OS power-profiles-daemon is installed by default.
Anyway, one might say that this feature may not save a lot of battery, but I am using my laptop running KaOS for my study and battery life matters even if it is just 20 to 30 mins longer.