In Arch Linux, mirrors are not automatically changed based on your location. Instead, Arch users use reflector to update mirrors.

Update Mirrors

Backup

Make a backup of the mirrorlist file before doing this, as it will overwrite the current one.

cp /etc/pacman.d/mirrorlist /ect/pacman.d/mirrorlist.bak

Run reflector

reflector --protocol https \
          --latest 10 \
          --sort rate \
          --save /etc/pacman.d/mirrorlist