KDE has Windows-style snap-to-halves or quarters by default. If you’re happy with those basic zones, it definitely works well. I don’t know if there’s a way to configure more complex zones.
Ultimately I went with 'Ultrawide Windows' [1], mostly because I like it better than the defaults and at the same time it is still simple to use. The Github page gives an impression of its capabilities and lists the hotkeys, but it is also available via the KDE integrated tools [2]. What I am still missing is a tool to simply define and use custom layouts.
There are plugins (Window Management → KWin Scripts) that add options, I see Tiling, FlexGrid, KWin QuickTile, and several more.