Chrome is getting a layout update that changes how you interact with your tabs. A new vertical tab grouping option allows you to move tabs to the left-hand side, saving space and making it easier to read.
Google’s reading mode will also change. Instead of opening in a split view, it will now take up the whole window, hiding the original webpage. To use the new layout, right-click on a Chrome window and click “Show Tabs Vertically.” You can then collapse the tab bar or turn on reading mode to focus on a single tab.
This update is rolling out to the stable desktop version of Chrome starting today.
Source: https://www.androidauthority.com/chrome-vertical-tabs-stable-3655470