Lift sofa upright, so i stands on one of the sides. If you look at it from above (like the animations), it’s now an L-shape (U-shape in the animations) with more space to move it around the corner.
There are a few couches where the seat sticking out past the front of the arms causes problems, and a few handrails in stairways that you can sneak between the arms of course, but probably nine times out of ten it's just the obtuse angle between the back and the arms that is your constraint. And that angle plus the rest of the couch around it looks a lot more like the cutout in the linked article than an L. Which is kinda the reason I brought it up.