I realize this is a rather minor issue, but maybe it's worth mentioning for the sake of the the overall Plasma-integration goal.
I think this feature is part of the Plasma integration for Libreoffice that, on other Linux distros, can be enabled by installing supplementary packages like
libreoffice-plasma (as discussed on Reddit/KDE here). LO-Plasma integration comes by default in KaOS, as far as I understand, since 2019.02 already, which provides LO as a pure Qt5/kf5 application.
But that part of LO-Plasma integration of showing LO files under Dolphin's "Create new" context menu is absent on my system, which is up to date.
This it what I see in KaOS:
It should be like this (tested in Kubuntu 20.04):