Just have to play it right. Slip in some details, get curious about what food you can order to your room, etc. You can always decide some detail is a deal breaker & not make the close
Or just be explicit and share. "Hi, I need to extend my stay from 3 nights to 2 weeks. I'm just returning from a high risk area of Italy and need to quarantine myself!"
"and I want to do it somewhere with a gym and pool"
Sounds like the original person intended on actually staying at the hotel for two weeks after failing to get their reservation cancelled, and was pleasantly surprised by the result. But yes, probably not easily replicable.
Many hotels in fact did reject refunds due to coronavirus cancellations including that of Jason Lemkin and the canceled Saastr conference.