The game is suffering from terrible screen tearing but there's no option to turn on Vsync or anti-tearing. What can I do?

Use AMD CCC or Nvidia Control Panel.

But even in Nvidia set High preset or manually set settings for some games possible add troubles. For AMD even more. So its a temporary solution only for Railroad.
You can find and add game .exe to video driver setting tool and change settings only for specific game.

Im set High and then manually change settings (use Nvidia Geforce card instead of integrated Intel) - and use always Vsync too. Currently I do not have any >60hz displays, but i know that many did have. Maybe you must choose some differ Vsync preset (adaptive or something like that). Bur in that case, dont forget that on different resolution frequency also usually differ. 120 hz display do not support 120hz for non-native resolution like 1024x768(maybe).