Global Themes - KDE Store
https://store.kde.org/s/KDE Store/browse?cat=121&ord=ratingGlobal Themes. Global Themes in Plasma are Meta- or Super-Themes, capable of changing multiple aspects of the desktop environment at once, like Window Decoration, Plasma Theme, Color Scheme, Icon Theme etc. In addition, one can define the complete Layout, like what panel to use where, the menu type used and much more. An example Global Theme:
how do I install a new KDE theme? - Ask Ubuntu
https://askubuntu.com/questions/1338590. Install the Theme/Style by either extracting and compiling it, or installing an RPM. Open the KDE-Menu and start the Control Center. Select "Look and Feel". Select "Style" if the package you installed was a style, or select "Theme Manager" if the package you installed was a theme. Select your theme or style. Click "Apply" Have fun!