SDDM runs on X11 by default, but you can force Wayland (experimental). An interesting deep-dive would compare login performance, multi-monitor handling, and session type selection on Arch.
sudo sddm --list-themes
sudo nano /etc/sddm.conf
Simple Desktop Display Manager (SDDM) is a modern display manager for Linux systems, designed to be fast, simple, and highly customizable. In this article, we'll take a closer look at installing, configuring, and using SDDM on Arch Linux. sddm arch linux