There is a scene after the the closing credits: Yelena Belova visits Natasha's grave, and is approached by Valentina Allegra de Fontaine. Valentina gives Yelena a mission to target the man she tells her is responsible for her sister's death: Clint Barton. This sets up Hawkeye (2021).
The opening credits is a montage of historical footage spliced with scenes of Natasha's childhood in the Red Room.