Inquiries do not block the calendar.
An Inquiry status is used when the guest asks the host a general question but hasn't submitted a "formal" booking request. Inquiries contain dates, listing names, and the number of guests, but do not have a reservation number, and they do not affect the calendar.
When creating a manual reservation, you can set its status to “Inquiry” if choosing not to reserve the dates for the guest. This status can be used when sending a quote.
For some channels (such as Vrbo, and Airbnb), a guest can send you an inquiry, which can be manually approved. Only if you change the "Inquiry" status to "Confirmed", the calendar will be blocked.
Learn more about what blocks the calendar.
Note:
In case you create a manual reservation and set its status to "Inquiry", we recommend not to assign the reservation to any specific sub-unit in a multi-unit. This is because other reservations can be received in that time being for the multi-unit, and might be randomly assigned to that sub-unit (as the sub-unit remained unblocked). If approving the inquiry (i.e., changing its status to Confirmed), it will cause a double booking to occur for the sub-unit.