I'm using Spacemacs Latex layer, which uses Auctex. If press space m v for the first time, the document viewer opens up in full screen over my emacs window. After, it only updates the window and keeps it under my emacs window. So to have the workflow that I want, I have to manually resize the emacs window to take up the left half of my screen and the Document Viewer window take up the right half.
There are two possible solutions that I can think of, I don't know how to do either or which is easier:
Get a pdf viewer for emacs and make the view command open the pdf in emacs in a new split window.
Make the view command somehow resize the Document Viewer window and my emacs window.
But presumably there is a standard solution to this problem? It's a pretty standard workflow so I expect someone to have figured it out.