Let’s look at the capacity planning and occupancy settings in Room Manager.

Daily occupancy, in this case, let’s see we have in the office 200 seats/desks so let set to 150 desks/seats bookable.

In this case, blocking employee booking will take place when occupancy is reached. 

Checking in without notifying anyone ahead of time however, is tricky. But now visitors can book the visit in advance very helpful for occupancy levels and understanding if there is availability in your office additionally when that daily occupancy is reached we can have a set of email contacts that need to be notified this can be receptionists,  facility managers or any number of people when bookings have reached maximum capacity by using SharePoint Notification services or a custom flow with PowerAutomate.