We decided not to include libreoffice on the iso. You will hear and see in the tutorial why.
It could not be any easier to install libreoffice.
sudo pacman -S libreoffice-fresh
Then you will need to see what package could be your language and install that as well.
If you can not find it with pacman. Remember to search in the AUR with packer, pacaur or yaourt.
The Arch Wiki should always be your first visit when encountering challenges.
We can also install any software package via the gnome-software. You have this application in all 3 desktops. But if you want to move to phase 2, 3 and 4, you will to get acquainted with the terminal.