Yes, portrait mode lets the
Yes, portrait mode lets the CarPlay display run in portrait mode! Waze, and all other applications, are much bigger now. It doesn't use the entire screen but most of it. If you use iOS 14 beta, you also get the icon bar moved to the bottom of the screen and they are bigger as well.
Definitely get the firmware upgrade to version 504. You can do it yourself too by going to gen5firmware.com for instructions. That's how I did mine vs waiting for dealer to do it (or brick it in many cases).