[Yetanfou]

Just adjust the width of your browser window to whatever width you prefer and the text will follow. That is, after all, what a browser was supposed to do: show text. If you use Firefox you can also open the inspector and select a mobile view (the two-screen icon top-right in the inspector frame/window) but that is more work for the same effect.

[StavrosK]

I generally just use the built-in reader view, so it's not really that much hassle, it's just slightly more work. Plus, reader view gets rid of all of the styles on the page, which would be nice to avoid.