Desktop theming
Desktop theming refers to the action of customizing and adding parts of your operating system to make them look nice & aesthetic. This is made easily accessible in operating systems like Linux distributions. However, you can practically do it on any type of system, depending on your skill.
I've tried theming before, and it was like talking one of the two pills. One is that I'd invest most of my daily life into tinkering and troubleshooting code so that I'll produce a memoriable result, or I take code and scripts that aren't rightfully mine to make the process much easier, but it's a dirty trick. In the end, I chose both.
There are tons of showcases of achivements from the community; the best one I found is r/unixart. UNIX is the first operating system created by Bell Labs which had incluences over modern-day operating systems. UNIX-like systems include Linux, MacOS, and a few others.