@Jennifer5259
Well...depends on what you mean when you say "easy" 😊
There are 3rd party apps that identify gaps and automatically offer those to guests at a discount for you. Of course, you would need to pay for the subscription and attach that service to your Airbnb accounts. Breezeway is one that does this. I believe there are other apps:
Breezeway
https://www.breezeway.io/blog/how-to-increase-airbnb-bookings#:~:text=Breezeway%20identifies%20these....

Some Hosts use Dynamic Pricing Software that will automatically reduce the rate of a gap night in order get the night booked, but they won't send a message to guests who might want to extend a stay for a discount. Some Property Mgmt Software might do it though (Hostfully, Guesty, Hostaway, etc.)
If you only have one listing, you can just create a Scheduled Message to use when you see those gap nights and offer the discount yourself without using a third party app.