Created attachment 103274 [details] Config file Changing the value of iconSize in plasma-org.kde.plasma.desktop-appletsrc does not seem to have an effect. When I change the default value in /usr/share/plasma/plasmoids/org.kde.plasma.private.systemtray/contents/config/main.xml however, the icon sizes change appropriately. Note that I've also tried this with fresh config file (mine seems to have gotten cluttered for some reason).
The only trace of "iconSize" I found in your config was alongside "textLines", this is for when you set the desktop to show Folder content, this is not system tray. Your "iconSize" config key for system tray would have to go to one of these: [Containments][1][Applets][5][Configuration][General] [Containments][55][Applets][59][Configuration][General] [Containments][60][General] (you can tell system tray config by the presence of "extraItems")
Yes, you are absolutely right; I added iconSize=3 under [Containments][60][General] then it worked. Sorry for the false alarm.