SUMMARY
This was reported some time ago as a bug but I was asked to enter a new ticket as a "wishlist".  I hope that some day users can go in to the KDE Keyboard Hardware and Layout menu and modify the cursor blink rate by turning it on or off, or by setting the blink rate manually.   

STEPS TO REPRODUCE
Reference: https://jurta.org/en/prog/noblink

*  IMPORTANT NOTE from #opensuse-kde:
[2020-10-21 15:51:57] <ndavis> <mdogg "The process under the "KDE" sect"> Don't use qt5ct with Plasma. It conflicts with system settings.



1. On KDE5 starting from Fedora 27 you can disable cursor blinking by doing this:
  Edit ~/.config/kdeglobals, set in the [KDE] section


OBSERVED RESULT
 I learned that when using the CursorBlinkRate= field, the number zero forces the cursor to present as solid vertical bar.  If a number other than zero is entered, the cursor blinks much faster than it used to but changing the numbers do not slow down or speed up the blink rate.  If you want solid use 0.  If you want fast, use a different number.  

Also, the following Internet Browsers still give me a standard blinking cursor just as they always have:
FireFox
Chrome
Opera

The Falkon Internet browser respects the 0 I entered in to ~/.config/kdeglobals and gives me a solid bar.


EXPECTED RESULT

It would be very nice if users had the option to at least have the ability to select "Cursor Blinks - Yes/No" from the same GUI they can select whether they would like NumLock to be ON or OFF during boot or the keyboard repeat rate in KDE.

SOFTWARE/OS VERSIONS

Linux/KDE Plasma: OpenSUSE Leap 15.1 (Kernel 4.12.14-lp151.28.75-default)
(available in About System)
KDE Plasma Version: 5.12.8
KDE Frameworks Version: 5.55.0
Qt Version: 5.9.7

ADDITIONAL INFORMATION
OS Type: 64-bit