You are correct, this is expected behavior in any browser. (when you paste a link, it leads to the link, when you paste a text, it searches on google).
However, in my Opera GX, the first option that 'was' being displayed, was to "search on google", which did so that when clicking enter immediately after pasting the link in the navigation bar, it was taken to the google search and not to the destination of the link.
For some reason opera reversed this, and then it went back to working correctly, I should have taken a screenshot or filmed it, I'll do that next time.