I'm using Plasma 5.12.7. In the main panel at the bottom, icons are too tiny at the default setting to be distinguishable. I can adjust the Task Manager icon size by expanding the height of the panel, but that doesn't affect the icons in the System Tray. If I make the panel tall enough, the system tray icons just get rearranged into two rows of tiny icons. None of the icon size settings in the System Settings seem to affect the System Tray.

Am I missing a setting somewhere that controls that? The System Tray appears to be a Plasma applet. Are those icons not controllable or use a different mechanism? If they are not controllable, is there a different System Tray applet that supports icon size adjustment?

1. Open ~/.config/plasma-org.kde.plasma.desktop-appletsrc
2. Find lines starting with "extraItems=".
3. Add "iconSize=3" on a new line after those lines and save.
4. Restart plasmashell from a terminal using this command: killall plasmashell ; sleep 1 ; kshell5 plasmashell

See also https://askubuntu.com/a/1030407/42522

ctimmerman wrote:1. Open ~/.config/plasma-org.kde.plasma.desktop-appletsrc
2. Find lines starting with "extraItems=".
3. Add "iconSize=3" on a new line after those lines and save.
4. Restart plasmashell from a terminal using this command: killall plasmashell ; sleep 1 ; kshell5 plasmashell

See also https://askubuntu.com/a/1030407/42522

This works perfect on me. Now my KDE desktop looks hot on my 1080p laptop. Thank You.