Sure, it has a scenario that let's you free play. There's one for CSX heavy haul as well (only on PC). In theory, you can free play in timetable mode but in practice you'll be stopped by auto switches and red signals if it's not a scheduled service at the right time.
When the editor is released (and we don't know when that will be) things like this will be more possible, at least on PC. Whether it will be possible on other platforms like PS and XBox will come down to how DTG decide to distribute user content.
