Read the wiki (https://wiki.artixlinux.org/Main/Migration#Prepare_the_repositories) or below.
# The gremlins repositories are disabled by default. To enable, uncomment the
# repo name header and Include lines. You can add preferred servers immediately
# after the header, and they will be used before the default mirrors.
#[gremlins]
#Include = /etc/pacman.d/mirrorlist
[system]
Include = /etc/pacman.d/mirrorlist
[world]
Include = /etc/pacman.d/mirrorlist
#[galaxy-gremlins]
#Include = /etc/pacman.d/mirrorlist
[galaxy]
Include = /etc/pacman.d/mirrorlist
# If you want to run 32 bit applications on your x86_64 system,
# enable the lib32 repositories as required here.
#[lib32-gremlins]
#Include = /etc/pacman.d/mirrorlist
#[lib32]
#Include = /etc/pacman.d/mirrorlist