@J262 That's not an extension; it's a date change.
You can send a request to your host to change the dates by following the instructions here: https://www.airbnb.com/help/article/913/how-do-i-change-a-reservation-for-a-place-to-stay
However, the change is only confirmed if the host approves it, and most hosts would be very reluctant to commit to a short-term booking over a year in the future knowing how uncertain circumstances in the nearer future are. When all is said and done, the better thing to do would be to cancel the reservation under the terms of its Cancellation Policy, and wait until you're in a better position to make firm travel plans before considering a re-booking. You will probably lose some of your payment this way, but this might be partially recoverable if you bought travel insurance with CFAR benefit.