Yes, I’ve never set it to anything else. I’ve been with three for years. My dad joined 2 months ago, plus I’ve 7 other family members, all on Three. None of us have that feature. I’ve looked at all their menus a little while ago, and no toggle for it like you showed.
I’ve seen maybe people on social media complaining this feature isn’t available on Three. You’re the first to say otherwise. Then tonight when I looked, and it’s on Apple support site, which was different to where you screenshot from, said US & Canada only.
In Phone on iPhone, Visual Voicemail shows a list of your messages. You can choose which ones to play and delete without listening to all of them.
support.apple.com