This is a KWin script that uses the new built-in tiling support for the upcoming 5.27 release (it won't work with prior Plasma versions)
More information about the new built-in tiles: https://notmart.org/blog/2022/10/kwin-and-tiling

It's useful especially with ultra-wide monitors as wide as 2 normal screens or more.

When maximizing a window it will maximize not to the full screen area, but to the nearest tile, having the final effect of one screen that behaves almost like it was 2 or 3 one near the other.
The effect can be configured with a blacklist of apps that will continue to maximize normally.