In Chrome there is this Extension: https://chrome.google.com/webstore/detail/alice-keeler-open-side-by/oohcehjlgohbhbljoepeoedbgcpcefod
Allows user to have links auto resize to half the screen. So that, if I'm using Chrome and there's another link I'd like to open side-by-side with the current page (say for a list of definitions to be used with the current page) when I click the link both the current page AND the link to be opened resize themselves automatically to occupy half the screen size and side-by-side. So, rather than having one full screen with a new tab that you have to click back and forth, you get two smaller screens equally sharing the screen real estate and right next to each other. Just from clicking the link.
Thing is, you need to have the extension installed to get this effect. I'm thinking that this may be some sort of code one could add to links. Sort of like target="_blank" in HTML. My thinking is that, if that's true, I could write specific links in web pages to open like this. Anyway to write the links to get this behavior? That, somehow, this is native to Chrome. And, by writing the links in the right way, we could get this effect.
As an aside, I know one can set links for new windows, and then drag the windows to line them up. Also aware of the idea of dragging to touch the edge in windows makes the focused screen automatically go to half size. But, the pages I'm making get a lot of low-experience users, so having the links do this on their own is what I need. If it is possible.