I think it is worth noting in the context of this thread that voice and video calling often is implemented using peer-to-peer technology (such as WebRTC). It might be enough for someone to call you for them to obtain your IP address, which gives a much more exact geographical position, sometimes down to the exact road you are at. Sometimes you need to answer the call before they get your IP address. But it might be contrary to user expectation that they can obtain this information just because you answer their call. Some messaging apps allows to turn off peer-to-peer connections in their settings, and use a relay server instead to mask your IP address.
It is also worth noting that you should never click on any link that goes to a site you don't already trust. Someone might run their own server at an innocent looking domain name, and send a link to you, in the hope that you will click on it so your IP address ends up in their server logs. This is an attack that is often used in practice, and that many are unfortunately not aware of.
Graphene1 Makes you realize how critical a VPN is for everyone.
Yes. Using a VPN, and not only specifically for the messaging app, but the whole user profile, would prevent most geographical deanonymization attempts, even if they get you to open an external app by clicking a link or such.
With that said, one would have hoped geographical caching of content, and peer-to-peer connections, and open links in external browsers and all of that weren't enabled by default, or at least could be easily disabled, or have adequate warnings on a case-by-case basis. Most messaging apps don't take geographical anonymity as seriously as one would had hoped. And this isn't an issue just for journalists either, domestic abuse victims who have protected living are also very vulnerable to getting tracked by their abuser this way.