In case you would like to strictly set number of daily appointments, without changing your daily availability, it is available with Rules automations.
Note that Automations → Workflows & Rules are available with Business and Enterprise subscription plan users (see full pricing and feature breakdown here).
Learn more about the Rules feature here.
Here's a quick guide on how to limit number of appointments to host.
Navigate to 
AI Scheduler → Automations → Rules page and click on the "Create Rule" button:
Click on the "Maximum number of calls" rule
Set "Rule Name" first
Select which events this rule applies to
An event can have only one rule of the same type
If you don’t see the Event in the events dropdown, you might have already applied a rule of the same type to that Event
Set the number of calls a closer can get for selected event
The list of Closers assigned to the event will appear below
In case you wouldn't like to apply this Rule to specific Closers, simply click on the dropdown menu in the Status column and set "Mark inactive".
This helps you precisely filter out individuals to whom the Rule should and shouldn't be applied