Trains have rolled through GTA since the top-down era, and screenshots confirm freight service continues in GTA 6. The locomotive follows American diesel-electric designs like GE's AC4400CW, and game files put its mass above 25,000 kg. That figure matters, because this is the one vehicle in the series with a long tradition of not stopping for anything, including you.
Ownership is not really the question here. Rockstar has not said if the train can be driven in GTA 6, and the series has gone both ways: San Andreas let you take the controls, GTA V did not outside scripted sequences. For now it is confirmed as part of the world, nothing more.
The Freight Train appears in official screenshots.
The community companion for Grand Theft Auto VI. Database, maps, guides and tools for Vice City and the state of Leonida.