We will be getting to Copenhagen Easter Sunday. We would appreciate recommendations for what to see and where to eat.
Get a start on what to see at https://www.ricksteves.com/europe/denmark/copenhagen and through the Tourist Information Office. I don't think you'll find many things closed due to the holiday. For instance, the great National Museum of Denmark is open all weekend, including Easter Monday, even though they are normally closed on other Mondays.
Generally speaking museums will be open, but shops will be closed during the easter holiday.