Here are some options to change how your Mac looks:
Change the wallpaper. You can do this in System Settings → Wallpaper.
Change the accent color: Go to System Settings → Appearance and select a new accent color. This will change the color of buttons, menu bars, and other interface elements.
Customize the dock: Right-click on the dock and select Dock Settings. Here you can adjust the size of the dock, change its position, and even hide it.
Use dark mode to change the interface to a dark color scheme.
Use third-party apps that can help you customize folders colors, files’ icons, widgets, and more.