Uh... that’s an HTML file—this is the emacs-orgmode mailing list. And viewing that page as rendered HTML in a browser, there’s no horizontal scrolling I see (and doesn’t appear to be with your styles as rendered at https://cup.github.io/autumn/append-to-array/). I was asking for an example of an Org mode file showing the issue that’s concerning you, not just proof that GitHub sometimes does horizontal scrolling.

If you’re asking about long lines in general that could be generated as export from Org-mode to any other format, such as Org *into* HTML, and then want to limit the lengths of the lines of the exported document code generated, in characters—and not what is displayed in width as pixels—then I don’t understand why you’d even be looking at Org-mode’s own link syntax. Line breaks in an Org file do not, in the general case, propagate into exported formats (except when line breaks are significant, like in source blocks). So successfully line-breaking in the middle of a URL in Org wouldn’t necessarily generate a line-broken URL in the resulting HTML (or TeX or PDF, source or rendered).

In any case, there will be no single solution to this—any ox library for Org export you use will have to be modified if they don’t handle line-breaks the way you want.