While studying for the RHCSA exam, I was doing research in the man page for journalctl. I understand the use of "--since" and "--until", in combination with the strings "yesterday" or "today". But I can't imagine a case in which I could use the "tomorrow" string, like in What's the use of "tomorrow", if the moment I am looking at the logs, there won't be any log entries for "tomorrow"?
I there anyone who can provide an example or a use case? It would be much appreciated.

That would show all of today's messages without having to specify an exact end time for "today".

That is to say if you were checking at 10 AM you would only have message up to 10 AM. If you were checking at 7 PM you'd have more messages up through 7 PM. Rather than having to specify 10 AM or 7 PM if you specify "tomorrow" it will find all matching records which at 10 AM "today" would only be those to 10 AM but at 7 PM "today" would be those to 7 PM. This way you can always specify the same syntax to get "today" messages no matter what time "today" you are running the command.

--until tomorrow is probably useless, but syntactically correct.
where is this example coming from?

I think I understand what you are saying, unless I am missing something in your reply. But in that case I would rather use the command Without "--until", as this seems to always give me the most recent journal entries, with "today" starting at "00:00:00".

I have found mention of "tomorrow" in the man page for "journalctl". Under the options "--since" and "--until".
The use of "--since tomorrow" seems nonsense to me. So I assume the only logical place to use "tomorrow", would be with "--until".
What I can't wrap my head around is that the moment I use journalctl, at the most I can read entries until "now" (which by the way is also an accepted string). I don't understand what the use is of displaying journal entries about "tomorrow", which in my mind seems indeed useless as well?

Some examples or use cases for which the use of "tomorrow" was intended would be helpful, either imaginary or real.

the only thing I can imagine is when the time is out of sync, so the log contains lines from the future (comparing to the actual/current date of the local host).

Probably journalctl contains the same/similar logic as the command date, so the same strings/syntax is recognized.

That seems a reasonable explanation. Continuing your chain of thought, then it could be that the logs are exported to a central server, where logs from different time zones are collected. In that case the use of "tomorrow" would be acceptable..
I have no experience with central collection of logs, so this is pure conjecture.