iOS 11: How to prevent an app from opening in slide over mode?
I finally found a way to get rid of that small window and make links open in a full browser.

I was using Google's Inbox to read emails and Chrome to open the links. As the OP was describing, clicking on a link opened a small Chrome window and because Inbox does not support Split View, the small window was not resizable. It turns out iOS remembers the size and state of the last time Chrome was opened in multitasking mode. 

I had to start some other app that supported Split View (like “Reminders”), pull up the dock, drag the Chrome icon to the top of the app, essentially kicking in Split View. Then I resized the Chrome window to be full screen. 

This way, now when I click on a link on Gmail or Inbox and select Chrome to open it, it comes in full screen.