There are features in OSM like power lines, pipelines, ski runs, fences, cliffs, hedges, traffic lights, marker buoys, ferry routes, bus routes etc. These aren't in the OMT vector tiles, to keep them small. (Some of them might be included since I last looked.)
The features that are there are included from a particular zolm level. If you want to make a global railway map - so you will show major railways at zoom 2, say - you would need to hack around, since the first zoom the railways appear on is 4 (or whatever).
What you can easily customise is showing those railways at zoom 4+ (or not) and the style of the lines.
If you want some of the features you mention rendered in your application you probably have to "Generate your own vector tiles from selected OpenStreetMap tags" as they also mention on their website.
[1] I'm not even a customer of them, just browsing their website.
The features that are there are included from a particular zolm level. If you want to make a global railway map - so you will show major railways at zoom 2, say - you would need to hack around, since the first zoom the railways appear on is 4 (or whatever).
What you can easily customise is showing those railways at zoom 4+ (or not) and the style of the lines.