It’s an update that’s mostly going to attract developers. The APIs help create AR and VR website components including 360-degree videos, home shopping applications, games, and more. The horizontal tab-switcher, meanwhile, is only available via an option in the Chrome Flags — experimental settings that typical users tend to avoid.
With that being said, Chrome Flags are easily accessed and changed, if you are interested in checking out the new setting. The horizontal tab switcher changes the format of the tabs menu (accessed via the number in the square box at the top-right of a Chrome tab) so that you scroll through the list left to right rather than top to bottom. It’s not just an aesthetic difference either; swiping in one direction can be a little comfier than the other for some users.
To access the horizontal tab scrolling, just enter chrome://flags/#enable-horizontal-tab-switcher in a Chrome tab to enable it and enter chrome://flags/#disable-horizontal-tab-switcher to disable it.