ArcoLinux aims to be fully themed and tweaked after your clean installation. You will get an XFCE4, Openbox and i3 desktop environment. Many of this theming is done in the ~/.config folder. One of the reasons to go for a clean install every time. But since 6.2 ArchMerge is rolling so you can decide to just keep working on your current version.
Choose your theme, icons and wallpaper.
Many tutorials will support you in getting to grips with these totally different desktops. Your applications and data will stay however the same like your browsers and music/video players.