@Lenny70 You need to understand the difference between Inquiries and Requests.
There is no "pre-approval" option for a Request. That option is for Inquiries. An Inquiry is a way of guests asking questions without commitiing to a booking. If you pre-approve it, that just means the guest can go on to book if they decide to. But many inquiries, you will never hear from again- they may have sent out Inquiries to a dozen hosts.
Never block dates for an Inquiry. It will make those dates unavailable to others who are serious about booking.
Also, you do not need to either pre-approve nor decline an Inquiry- all that is required is that you message back within 24 hours.
A Request is different- you have 24 hours to choose the option Accept or Decline after communicating with the guest and checking their reviews to determine whether you want to accept it or not.
When you accept a Request, Airbnb proceeds to charge them and the dates will be automatically blocked.