"In the video game industry, games as a service (GaaS) represents providing video games or game content on a continuing revenue model, similar to software as a service.
[...]
Games released under the GaaS model typically receive a long or indefinite stream of monetized new content over time to encourage players to continue paying to support the game. This often leads to games that work under a GaaS model to be called "living games", "live games", or "live service games" since they continually change with these updates."
GaaS monetization can't be achieved without a central online service. Even with Hitman 3 a lot of content is locked behind the online requirement.
You can bend the definition as much as you want but this is what most people mean by" live service games".