If I understand what you're asking, then no, you don't need a third-party launcher to use the widgets I'm using. They are third party widgets though ... not stock with the phone.
UCCW is a custom widget app that has some pre-loaded widgets, and the ability to make your own. I even made my own weather icons for that widget. It also allows hot-spots to launch other apps - which is how I tied my alarm clock and weather app to the widget.
The calendar is "simple calendar" widget, in the play store. Out of the box, the widget is pretty ugly ... but with some careful customization of the settings, you can make it look quite a few different ways. And the fact that it too is able to interact with your calendar, and scroll ... it's perfect. I can quickly see what i have on my agenda, scroll through my calendar, and then jump into my actual calendar app if I need to make another appointment or whatever.
the ONLY thing I dont like is that the weather on the top widget is pulled from some pre-set weather provider, and it's never quite right. It's close enough, but never perfect. Also, note that the current temp is not within the high-low range shown immediately to the right of it. That makes no sense!!! LMAO. But I can live with it. Whether it's 75F or 78F, I'm not gonna care. I just like to see generally where the temp is, and that's good enough for me.