It's downloading now on my Pixel 4 XL. It's a feature drop month too. Cool.
I have been changing app icon shapes, fonts, and color scheme every few weeks since owning my Pixel 4. And yes....it's all predefined shapes, fonts and colors. But Google did add more to the selection choices. I just changed my Home screen settings a little with some of the new options.Sweet! I'll have to check mine. I was reading about the December drop, and it says we'll be able to change icons. I'm assuming it's pre-made icons that are already in the system, but I'd love to see it!