Washington Post just published an article on this - Playground Safety Tips.

https://www.washingtonpost.com/goingoutguide/playground-safety-tips-coronavirus/2020/10/07/d237b3a4-01b4-11eb-b7ed-141dd88560ea_story.html

Some useful tips, I think.

I take my 18 month old to the park every day. I wear a mask, we use hand sanitizer before and after, and I try to keep my distance from other kids/adults. If my kid starts “playing” with another kid and they are getting close, I ask the parent if they are comfortable. I think this is the most important thing to do. Our neighborhood park is pretty crowded with the same people, so I think doing what makes everyone comfortable is the most important thing to keep on mind.