Someone asked me if it was possible to have a more gnome-ish look in kde. What he meant was without titlebars and maybe some more roundness. For those who shouldn't know, you can. Some window decorators have that option in their settings. Breeze, Classik, Breeze enhanced, Sierra breeze enhanced, Lightly...and some have that setting in their window specific tab. In there you can set to disable titlebars for all or specify only certain. Dragging an unmaximized window can be done either by setting it to an empty space within the window or using the alt or super key. If you're a hardcore keyboard hater you can also make a small desktop application which you can put on your panel which does just that, put a drag cross on the active window. As for close/max/min buttons, most kde apps have the possibility to have a close button on the toolbar. As for maximizing/unmaximizing, dragging to the top does the trick. Or, you could use widgets like, in this case, active window control or panel buttons to control that. Screenshot shows the result. Active window control widget, more rounded lightly application, rounded breeze icons and rounded windows with classik window decoration.
https://imgur.com/a/z0Z2cbd
Disabling titlebars is also a good option if you run a tiler like krohnkite to save some real estate on a small screen.