The original answer is archived btw: web.archive.org/…/is_there_anyway_to_run_commands…

Is there anyway to run commands through KDE connect?

if you have some commands already defined in KDE Connect, you can long press on them and get a custom URL for them. when you open the URL in any way (through the web browser, KLWP or Tasker etc.), the command will be executed on the other device.