Update 1/13: In another update (version 220.127.116.11), the normalized app icons were removed and are now back to their original size. The feature was likely just a bug. This update also fixes the gap between the favorites tray and onscreen buttons in landscape and the non-grayed out buttons when the launcher is opened.
The Google Now Launcher received quite a few updates in version 18.104.22.168 of the Google app. The launcher, which resides within the Google app, now has landscape orientation and normalizes the size of app icons.