You can do that with parallel tracks, waypoints and priority signals. You route your slower line along a parallel track (with a waypoint) and place an ordinary signal before the join. On the faster line, you will use one or two priority signals instead. I attached a screenshot with this example.

I'll give it a shot but I'm not sure it'll help much. The freight trains I run end up being 1-2km long (I run industry multiplier) so it's often just easier to run 4 lanes of parallel track so that never shall passengers and freight meet. Also from your diagram it looks that you still have to set the slow line to a specific side track 100% of the time and the express line to the other track 100% of the time. I'm still not sure if you can set a line to choose either the central track OR the side track if one or the other is already occupied.

I cannot see how a train can give way to another if they are on the same track. They cannot fly! If you have very long trains, dedicated tracks and RoRo stations are probably best anyway.

Yeah the game would need to have dynamic path-finding for trains to switch to unoccupied tracks, which TpF 2 doesn't have, unfortunately. The only place it exists is in stations, with the alternate terminals feature.

Is there a way to make zig - zag station (the station with just the track) kind of a hybrid station/signal. I use these as alternative pathfinders. But when trains have a clear signal they still need to stop at the zig-zag for 10 seconds before proceeding.

Wazza?

https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=1920437817&searchtext=

Putting the title in german causes problems for every other language on the planet......

What is missing is an option for lines NOT to stop at stations. There may be a way to do that with a mod, adding and removing stations from lines at a potentially high frequency. I doubt it would work well.