Is there a delay to include call function modification in a scheduled cron task?

What happens excalty, call functions are cached ?

They do not get cached.

When you schedule a cron job, it stores a record in the database to trigger a hook with certain parameters at a time/date. No code is cached.

So when that time comes, the code is loaded and run from the disk as it is at that time, not when it was scheduled.

For example, if I schedule a cron job for tomorrow that writes the word “hello” to a file, then immediately change the function to instead send an email, when the cron job runs an email is sent.