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Yes, Zorin uses Gnome but it is customized. You don't have this Mobile UI Look by default. You have a Taskbar, a Startmenu and Desktop Icons. But You can turn off all these Stuff and then You would have this Mobile UI Look. By default you would have that on Distro's who use the so-called Vanilla Gnome Desktop. That is the Gnome desktop without Customizations. There You must add Customizations by yourself.
For Plasma 6: No Zorin doesn't have that. Zorin is based on Ubuntu 222 LTS and has the Plasma Version out of the Repo.
If You are interested in the Plasma Desktop maybe KDE Neon would be a better Option. This Distro comes from the KDE devvelopers woh are developing the Plasma Desktop. There You have a solid Ubuntu LTS Base with an up-to-date Plasma 6 Desktop.