No. A reservation request can only be accepted or declined, you can't do a counter-offer, or amend the rates. Your only options if you want to offer a different rate to the guest, are (1) to decline the reservation request and then send them a special offer, or (2) to accept the reservation request as is, and then do a change of reservation, where you change the total $ amount of the reservation, or change any of its aspects (eg dates, total price, which listing it is in, etc)
An inquiry is different than a reservation request. With an inquiry you can send a preapproval, or a special offer, or decline, or just keep dialoguing.