You should read about kcmshell5 and other KDE cli tools. That’s probably not all command you need to know, sometimes you need to reload module or all Plasma – read about command line options for kwin and plasmashell. You also need to know config file names and parameters (required for modifying with kwriteconfig5) – most of them are placed in ~/.config directory. If you need something more advanced, read KDE System Administration - KDE UserBase Wiki.
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