Our company is open from 6:00 PM to 5:00 AM. Is it possible to show on the calendar only these hours, without split at midnight?

Open the resource settings. Set the checkbox Visible hours and set the start and end times.

You can also set the desired time period in the manager's table. Open the table settings. Select the period Yesterday, Today or Tomorrow. Set the checkbox At specific hours. Then set the start and end hours.

See the example of a widget for a client in action: