KDE is an international technology team creating user-friendly free and open source software for desktop and portable computing. KDE’s software runs on GNU/Linux, BSD and other operating systems, including Windows.
If you encounter a bug, proceed to https://bugs.kde.org/, check whether it has been reported.
If it hasn't, report it yourself.
PLEASE THINK CAREFULLY BEFORE POSTING HERE.
Developers do not look for reports on social media, so they will not see it and all it does is clutter up the feed.
You need to set the scale in the sddm config file. I had the same issue where Kde properly set the theme but not the scaling. Here is a guide from the arch wiki
https://wiki.archlinux.org/title/SDDM#Enable_HiDPI
To find your screen dpi I think there is something in KDE display settings.