Chaotic AUR

First, install the primary key - it can then be used to install our keyring and mirrorlist.
sudo pacman-key --recv-key 3056513887B78AEB --keyserver keyserver.ubuntu.com
sudo pacman-key --lsign-key 3056513887B78AEB
sudo pacman -U 'https://cdn-mirror.chaotic.cx/chaotic-aur/chaotic-keyring.pkg.tar.zst'
sudo pacman -U 'https://cdn-mirror.chaotic.cx/chaotic-aur/chaotic-mirrorlist.pkg.tar.zst'
Append (adding to the end of the file) to /etc/pacman.conf:

[chaotic-aur]
Include = /etc/pacman.d/chaotic-mirrorlist