I know that in iOS, even if web developers stipulate user-scalable=no the user can turn on zoom in accessibility options, and with a triple finger click, zoom in on these pages.
I am wondering if there is a way for BlackBerry users to do the same?
Not that I’m aware of. On iOS, three-finger magnification is really a separate OS feature: when you use magnification to zoom a web page, the text doesn’t get re-rendered at a higher resolution as it would with browser zooming, so it looks blurry if you zoom in far enough. But it’s a decent work-around. Blackberry has no magnification app that I’m aware of. (Typically magnification needs to be an OS feature, not an app, since it requires full screen access and other special privileges, which apps typically are not allowed to do.)