Thanks! Unfortunately my printer did not appear.
HP Linux Imaging and Printing System (ver. 3.21.8)
HPLIP upgrade latest version ver. 1.0
Copyright (c) 2001-18 HP Development Company, LP
This software comes with ABSOLUTELY NO WARRANTY.
This is free software, and you are welcome to distribute it
under certain conditions. See COPYING file for more details.
error: HPLIP upgrade is disabled by Archlinux for security reasons, see
https://bugs.archlinux.org/task/38083 - if you like to upgrade HPLIP, use the Archlinux software package manager pacman.
Done.
lpr: Error - The printer or class does not exist.
error: Print command failed with exit code 256!
Done.
I run pacman -S hplip and it says it installs to version hplip-1:3.21.8-1 but I still get the same error.