How do you design an online event? An online event needs the time to automatically reconfigure by the participant's location. As an online event, the organizer's location is irrelevant. It may include several places (and thus time zones) with an organizing team. More important location-wise is to indicate which online platform the event will be on: Zoom, Teams, GoogleMeet, something else...
Yes, timezones are critical to online events where you may have people participating from more than one timezone.
The bad news is that CiviEvent isn't timezone aware. You can certainly use links to the online platform of your choice, and lots of CiviCRM users do make use of CiviEvent for virtual events, but you'll want to specify the timezone in the title and/or text of the event to avoid confusion.
There are some timezone aware bits in CiviCRM, maybe most of them, but CiviEvents is tricky and an earlier attempt to fix it failed.
Likewise, CiviEvent doesn't itself know what platform you're using - you have to put the event information in the description and the email sent out (unless you're using an extension that is connected to your event platform).
I use a Drupal webform to handle the registration process and in the email sent out specify the time and link.