A fresh Lep 16.0 install with XFCE does apparently fail to configure auto login, or I just missed the relevant knobs in Agama. I came up with this solution:
==> /etc/greetd/autologin.toml <==
[terminal]
vt = 1
[default_session]
command = "cage -s -- /usr/bin/gtkgreet"
[initial_session]
command = "startxfce4 --wayland"
user = "local_user"
==> /etc/systemd/system/greetd.service.d/override.conf <==
[Service]
ExecStart=
ExecStart=greetd --config /etc/greetd/autologin.toml
But since the used greetd is Wayland-only, I installed pattern “xfce” and package “lightdm”, and adjusted /etc/sysconfig/displaymanager:DISPLAYMANAGER_AUTOLOGIN=.
The instructions in SDB:Change_Display_Manager suggested to use update-alternatives --set default-displaymanager /usr/lib/X11/displaymanagers/lightdm, but systemctl status display-manager still points to greetd.service.
To change the default, run either systemctl enable --force lightdm, or systemctl enable --force greetd.
The Wiki has been adjusted to reflect the current reality.