James Gunn has confirmed that there will be multiple Guardians of the Galaxy Vol. 3 post-credit scenes. The Marvel Cinematic Universe is not unfamiliar with dramatic ending sequences that left viewers wondering what will happen next.

In response to a recent fan inquiry on Instagram, Gunn said that the next superhero film will have not one, but two post-credit sequences. Fans will be pleased to see that the Vol. 3 post-credit sequences adhere to the format, even if this may not come as a surprise given that the majority of Marvel Studios movies include two post-credit scenes.
While the exact timing of the post-credit sequences is unknown, it is customary to include a mid-credit scene and a little stinger after the entire credits have run.
The Guardians of the Galaxy Vol. 3 post-credit scenes were discussed by James Gunn in the statement below.

James Gunn once again wrote and directed Guardians of the Galaxy Vol. 3. Star-Lord, Gamora, Drax, Kraglin, Nebula, Mantis, Rocket, and Groot will all be played again by MCU veterans Chris Pratt, Zoe Saldaa, Dave Bautista, Sean Gunn, Karen Gillan, Pom Klementieff, Bradley Cooper, and Vin Diesel. Will Poulter, Chukwudi Iwuji, and Maria Bakalova, newcomers to the franchise who have been cast in the roles of Adam Warlock, High Evolutionary, and Cosmo the Spacedog, respectively, will also be introduced in the threequel.
The space-traveling group was most recently seen in Marvel Studios’ Guardians of the Galaxy Holiday Special, a Disney+ original special that was produced concurrently with the planned threequel. In the holiday special, Drax and Mantis throw Peter a Christmas party complete with an appearance by his hero from boyhood Kevin Bacon in an effort to cheer him up.