Create a calendar on iCloud.com
You can create and manage one or more calendars and access them on any iOS device, iPadOS device, or computer that has iCloud Calendar turned on.
In Calendar on iCloud.com, tap the Action pop-up menu in the bottom-left corner, then choose New Calendar.
Type a name for the calendar, then tap Return.
Your calendars are listed in the sidebar on the left. If you don’t see the sidebar, tap the Show Calendars button below the calendar.
You can view as many calendars as you want at the same time.