Every project has its own unique calendar link. You can add as many as you want to Google Calendar, Microsoft Outlook, or Apple Calendar.
Each project arrives as a separate calendar in your calendar app, which means you can:
To add another project, open that project's Calendar, click Calendar Integrations, and copy the link the same way.
You can also connect the Workspace Calendar link at the same time if you want a combined view of everything in one place.