KDE config files can be changed on the command line using:
kwriteconfig
And viewed using
kreadconfig
Power management is in:
~/.config/powermanagementprofilesrc
And
~/.config/powerdevilrc
You can feed changes to the file via kwriteconfig via the command line OR create a duplicate file with different settings and use rename commands in a script file to switch back and forth.
E.g. rename the file to "powermanagementprofilesrc.backup" and create and rename a custom file with the settings you want like "powermanagmentprofilesrc.one" to "powermanagementprofilesrc". Rename them back and forth via a bash script to switch "profiles"
To apply changes you'd need to then run qdbus:
qdbus org.freedesktop.powermanagement /org/kde/Solid/PowerManagement org.kde.Solid.PowerManagement.reparseConfiguration
And then to load the new config in your current session:
qdbus org.freedesktop.powermanagement /org/kde/Solid/PowerManagement org.kde.Solid.PowerManagement.refreshStatus
So either use kwriteconfig and qdbus in a script OR make duplicate config files and a bash script to copy or rename the configs as needed plus qdbus to apply the changes to the current session.
There may be a much simpler way of switching profiles already actually defined within the exisiting config files (e.g. battery saver vs performance) using qdbus but I'm not sure how to do that myself. Possibly using:
org/kde/Solid/PowerManagement/Actions/PowerProfile
EDIT2: Sorry this is a very long post! Just to say if you're new to linux and want to understand a bit: qdbus is a tool for QT based applications (including almost all of KDE which is build in QT) to interact with DBUS which is basically the messaging system in linux between processes.
So when you run qdbus on it's own you'll see a tree of processes that are interacting with QT processes. Then if you run qdbus & the name of a process like "org.freedesktop.powermanagement" you'll see what QT processes are running with/under it. Then if you run dqbus and add that connected process like "/org/kde/Solid/PowerManagement" you can see what strings and options are available. Then you can run qdbus to see more detail or change a setting/string.
Hope that make sense!