As the title said, I customized my system according to what I liked. It's probably a mess of features and design elements cobbled together from the OS's I've used (or would like to use).
There's also some features I've customized that is hard to show via screenshots, like mouse gestures to move windows around different screens and virtual desktops.
I don't think I've achieved everything I want here, but it has gone way further than I've imagined it'd go.
While KDE Plasma offers a whole lot of options for customization, it's really daunting especially if you're just new to it. What really helped me is to just go with a little bit of customization and tweaking at a time. As I got more experience, I started to want more and more which lead to a lot more customization and tweaking.