You can position the displays any way that you like, and that results in the video layout that works for your particular use.
All are completely legal, there is no wrong layout.
(I have my two displays, main display on desk level, and the second is currently attached to the wall, directly above the main.)
When I used two displays I liked having them tight together and just slightly angled. Some people on another project were using wide screen monitors and used one in landscape and one in portrait. The portrait display was the code window. Didn’t have to do much scrolling.
My preference is the main screen directly in front and secondary screen canted at an angle on the right side.
I use the front screen as the main working screen and the right screen is kind of a storage screen for open apps and other items that I might go to from time to time