Yes, I think booking an award flight and then cancelling it is one way to do it if you don't mind paying the cancellation fee of an award. Though I'm not sure what would be the new expiry date of your miles once they get re-credited.

I think I did the exact same thing during COVID. I remember redeeming a round-trip itinerary around 9 months later using miles due to expire soon. At the time of making the booking, I was hoping quarantine would be lifted by the time I was due to fly my itinerary. Didn't end up happening so I ended up cancelling the ticket. If I remember correctly, I was told the miles will expire one year from the date they were re-credited to my account. So essentially this booking-and-then-cancel mechanism helped me extend the expiry date of my miles by about a year and 9 months.