Hi Trumori,
There’s a couple ways to get the curtain wall panel geometry.
Typically you want a particular Wall or Wall Type before getting the panels, which you can do by the Analyze Curtain Wall. This allows you to get Grid info as subsequent Panels. Here you could change the Type if need be.
Here are a couple less precise ways to get the Panels
https://www.rhino3d.com/inside/revit/beta/guides/revit-curtainwalls