Well I installed (eventually) 16 Core r1 and this is it with KDE dekstop:
Cursor size change in this manner:
Added Windows 11 Menu in KDE:
Windows 11 OS Theme.
New Wallpaper - Darkest Hour (especially if you are using Windows 11 
.)
Proof this is on Zorin 16 Core r1:
I installed KDE via the terminal using:
sudo apt-get install kde-full
Nice isn't it 
. I did this last week with Cinnamon on Zorin OS
sudo apt install cinnamon-desktop-environment
Well I will see if I can break it by installing ALSA then removing Pulse Audio - could only do that in my initial Devuan 3.1.1 install. On the notebook I have an old Dell Latitude E6500 running xfce of Devuan 3.0 and not even plugin override of Pulse Audio needed!
Also need to try to see if I can replace Systemd with SysVinit!
Also I refuse to use Cinnamon anymore as it is dependent upon Pulse Audio created by the same guy who invented SystemD! 
In my opinion, KDE is all about the apps. The impeccable app meshing in KDE is what makes it wonderful. So I recommend for those wanting to use KDE on Zorin to import all of the bleeding edge KDE repos to get the latest version of KDE apps. In your screenshots I noticed that you have a very old version of Plasma. The current version is 5.22.5 and the difference is day and night.
That's because this is a fresh install and pointed to Ubuntu repos - I don't intend using 16 as my go to - Devuan 3.1.1 is my go to - been using it since Christmas as SysVinit is much more secure than SystemD boot process. 
And that uses an older version of KDE but it is usable - I was even able to use Remmina Remote Desktop in Devuan to log in to my Z drive at work and move things to Office365 with one log on instead of three when I was using a VM of Windows 8.1 primarily to access an Outlook account I could not get to work in Evolution! My only other comment is that 'bleeding edge' normally leads me to reach for the nearest pack of 'band aid'!
A modified desktop with one of my own walls:
Just to add that in KDE if you change the cursor theme and you still get Breeze showing on the desktop you just edit the cursor theme file as stated here:
You also need to edit the top line to to change to the name of your chosen new theme.
Forgot to add, Konqueror still has issues - could view most of the site but not the forum - just a white page! The other pages of zorinos could be viewed easily.
Whilst the Devs have correctly installed Evolution they should have had its companion, Firefox ESR available for Corporates as it is the only version of Firefox that can be locked down at the IT Department end!
Well guess what? It appears KDE has gone down the same route as those clueless fools at Gnome - Pulse Audio is embedded in 5.22! According to someone on Artix forum they have managed to remove all pulseaudio with the exception of libpulse to prevent breaking the system. The archwiki is quite lengthy on sound config!
https://wiki.archlinux.org/title/PulseAudio/Examples
I can see I have got my retired work cut out!
I suspect, they will keep us all busy, for a long time...
What's the issue with Pulse Audio? It's a part of the system, why do you want to rip it out?
Haha nice! We should call it Korin!
Partly because it was written by the same guy that wrote systemd and partly because as a professional musician on the Devuan forum states that all it does is add bloatware and latency. Plus I want to be able to have a system that I control. That is the whole point of GNU/Linux - power to the users, not the corporates like Red Hat who want to be the Microsoft of the Linux world = bloatware!
https://unixsheikh.com/articles/the-real-motivation-behind-systemd.html
Problem with Cinnamon is it relies on Pulse audio.
SWARF!!! has more Linux skill then most of us, its well within his means to rip out a key component that would break his system, then replace it with something else, and have his system working normally again.
If I tried to do that, I'd be at a white screen of death before you can say by Granthars hammer, by the sons of woven, I avenge you.
I want the win 11 start menu on zorin OS Core but I don't want to install KDE can u give some ideas?
I replaced mine with Pipewire. I don't think removing PulseAudio will break KDE, did it break? Personally I find it indistinguishable.
I still use Pulse on Zorin
You can install Arc-Menu Gnome Extension
