There is kde-inhibit --screenSaver <command> provided by KDE.
But these days, I would just recommend everyone to use systemd-inhibit --what=idle --why=<because> --who=<myself> <command> instead. Works across desktops and does the same thing.
What should I put in the <command> part?
Anything that runs as long as you want the block to be. Usually sleep is a good one, use sleep infinity if you want the blocker to never go away until the systemd-inhibit process is killed manually.
Would yes command work ?
Aaaah, that's probably what Plasma is doing.
Not KDE but might be similar: For the MATE desktop it is mate-screensaver-command --inhibit. I would expect something similar for KDE.
I don't know if this fits your use case (you didn't describe what you want to achieve in detail), but commands that can possible help if the screen did lock (or turn off):
loginctl unlock-screenkscreen-doctor --dpms onWasn't that. I want to keep the screen on. No sleep, no lockscreen, no blackscreen, etc.
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.