On my 13 inch screen with 3200x1800px I adapted all fonts to 230dpi which is ok in most cases.
Also in Settings, I could change Icons of the KDE Theme to 64px.
Only the Icons in the statusbar at the bottom right corner (velocity, Network,...) are still only about 16x16 px, which is barely readable. They seem ńot to obey the same rule.
Where can I change them?