WeWork isn't an open plan office. At least, not the one I work in in London. We just pay an extraordinary amount of money for a small glass-walled room. We internally have an open plan office, but that's just because we opted for a single WeWork room.
At least in my NYC WeWork the sound isolation is so bad that it might as well be an open office. I can clearly hear all the phone conversations my WeWork neighbors make. I assume they can hear mine as well.
The two I've been in in seattle have been basically silent inside our office.