Multimonitor issue black external screen on login

Any updates on this, I recently ran into the same issue.
And the monitor screen is just black.
I'm using the latest dragonized version.
And I have the same issues with autorandr as mentioned above

Moved to a new topic, as things change all the time in rolling (Arch based) distros and user HW/SW setups are different.

KDE has its own utility to handle multi-monitor setup.
Look in the system widgets area for Display settings (IIRC Win+P).
Use that widget to set monitors layout.
Then right-click on new monitor to configure (wallpaper, etc.).