In a Scheduling Link page, there's a timezone drop-down menu below the calendar (I think it should be above, but that's a separate request.)
In the Events Page there should also be a drop-down timezone selector. Because a lot of people have the default timezone on their profile (GMT+12) and so they get confused by the date/time of events.
The vast majority of users don't know they need to go to their profile and set the timezone. Might as well give them that option right there, when they're about to register for an event.
The confirmation email also gives the time in their supposed timezone, and if they haven't set it, it continues to confuse them 😅