Change the booking price based on the number of guests

Desired Features:
Customer:
Allow customer to select number of guests when booking.
Host:
Allow host to set a maximum number of guests per listing. Allow hosts to charge a fixed amount per guest per listing. Allow hosts to charge a fixed amount per guest per listing after a certain number of guests (For example: $1000 includes up to 2 guests, $300 per additional guest after 2)

Yes, it’s possible already - please enable multiple places per booking in HivePress/Settings/Bookings, then there will be the Places field in the booking form and hosts will be able to limit the quantity (you can rename Places to Guests via Loco Translate, or if you use RentalHive this field is already renamed).
The booking price is multiplied by the number of guests, but there’s no option to provide discounts depending on the guest number yet (it’s possible to do this depending on the number of days though).