Is it possible to make one calendar for all resources?

Yes.
Let's use the example of a general holiday schedule.
First, create a rule for holidays.

In this rule, configure a calendar with the desired schedule.

In the calendar settings, click the menu icon.
Then select Save schedule.
Enter a name and save it.

The saved calendar will now appear in the list of shared calendars.
To use it in another resource, open that resource's calendar settings and click the menu icon.
Select the desired calendar from the list.

This allows you to create shared calendars.
If you update the schedule in a shared calendar for one resource, the changes will automatically apply to all resources using that calendar.

If you want to update the schedule for only one resource that uses a shared calendar, first detach the calendar from the rule.

To do this, open the calendar settings and click the menu icon.
Then select Schedule for this rule only.

You can now modify the schedule in the calendar.
This time, the changes will only affect the current resource and will not impact other resources.

To delete a calendar, ensure it is not used in any resource rules.
Otherwise, you will not be able to delete the calendar.

Open the calendar settings for rules.
Click the menu icon.

Then, click the menu icon next to the calendar you want to delete.

Delete the calendar.