The CDC put out some ways to celebrate Halloween safely:
One-way trick-or-treating where individually-wrapped goodie bags are lined up for participants to grab and go
Open-air, outdoor costume parades with a small group of people
Outdoor costume parties
Open-air, one-way walking haunted trailers.
Visiting pumpkin patches or apple orchards where people use hand sanitizer before picking pumpkins and apples
Outdoor Halloween movie showings with others