Yes the example from official docs work for the first channel but the NTP has another channel with the ending :string, see attached picture of both channels from HABmin. The first is type datetime and the second one is type string and I guess it is possible to add the Date Time Format for the string as a parameter in .items file.
Another example of a channel with additional configuration parameters is from one of my Z-wave devices where it is possible to invert the feedback position and control direction in HABmin but I do not know how to do this in textual configuration in .items file.
These are set through configuration parameters - I guess it’s the same as any other parameter configuration for any other binding as it’s definitely not read by zwave. You’d need to look in the source of the _channels.xml file to see what the naming is for the parameters.
It can be done in text files as well, but I don’t have an example of how to do it as I always use the UI. The format for items is the same for all bindings though so I would look in the OH docs as it should be described there.
If you’re after specific configuration for certain channels (and really there is very little) then you can check the channels definition file -: