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:
Assign a different color to each project
Toggle individual projects on and off without disconnecting anything
Keep your personal appointments visible instead of buried under project items
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.
Read the full article: Can I connect more than one project calendar at a time?