The feature called Split window is currently undergoing testing on the Edge Canary version. When activated, a new button will appear next to the address bar allowing you to split the Edge window into 2 windows containing separate tabs, thereby enabling you to browse two web pages simultaneously.
If you're using Edge Canary, you can visit edge://flags and search for Microsoft Edge Split Screen > Enabled.
Restarting Edge will add a Split window button, resembling a divided window, near the address bar. This setting will also be available in Settings > Appearance of Edge.
Alternatively, you can open a new tab from a new window, and the address bar will be shared between the two windows.
Or, you can open links in the Split window by right-clicking on the link and selecting Open link in split window.
In Split window mode, 2 tabs are grouped together, forming a pair of 2 web pages displayed side by side. This allows users to create multiple pairs of parallel tabs for simultaneous browsing, which is ideal for those who need to reference and cross-reference multiple web pages at once.
By default, the window will be evenly split, but you can also customize the split ratio by dragging the three-dot button on the splitter bar between the 2 tabs to the left or right.reddit.com