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, click the Action pop-up menu in the bottom-left corner, then choose New Calendar.
Type a name for the calendar, then press Return.
Your calendars are listed in the sidebar on the left.
You can view as many calendars as you want at the same time.