In the Workplace Web Portal, you can see who is in the office daily and invite your colleagues to collaborate.
To do that:
Go to your resource booking page.
Use the filters to select a date you are interested in.
Book a desk for the day.
Click Teammates.
Find the teammates you want to catch up with and click Invite.
This will invite them to book a desk on that day.
You can also invite teammates directly from your Dashboard.
Also from the Schedule page: