What makes Linux appealing to me is the extent of customizability, but I didn’t find many answers when looking up with desktop environment is them most customizable. Some say KDE is most customizable than say, Gnome, but doesn’t Gnome support CSS customization while KDE doesn’t?
Gnome is technically one of the most customizable, but it is opinionated which means the end user isn’t supposed to change anything, only devs (Like Ubuntu or Zorins customizations). Kde Plasma on the other hand is designed to be easily customizable, you are supposed to make it your own without having to install external software (for example Gnome requires you to manually install the extension manager while it is built in with kde). Then there is Xfce, which is also very customizable but has little built in. This is because with Xfce you are supposed to customize with external software (for example using plank as your dock).
So basically, Gnome is for when you want an opinionated DE (or want to make a distro and have it certain way), KDE is when you want something very customizable and Xfce when you something customizable and modular.