DC Acts Like Marvel
The Batman doesn't have a post-credits scene in the traditional sense, but it does leave fans with something unique and interesting after the credits.
The End-Credit Friendship
Barry Keoghan offers a riddle to Riddler: The less of them you have, the more one is worth' the answer being "Friend" and there they share their maniacal laugh.
It's None Another Than JOKER
Fans with any basic knowledge of Batman are sure to know that Keoghan was none other than the Joker, the iconic Batman villain.
GOOD BYE <?>
The post-credit scene feature a cursor that types "Goodbye <?>" (way of Riddler to communicate with Batman) and later we see a URL which actually exists: Rataalada.com
The Winged Rat From Batman
“El Rata Alada,” which means “the winged rat” in Spanish, was one of the major clues The Riddler left Batman. A marketing gimmick to allow fans to engage with the film beyond the film
Matt Reeve's Misdirect
This hints at a sequel to the greatest detective Batman with Riddler's comeback or Joker, however, Matt Reeves advised not to expect it to be setting up a sequel.
Batman's "Rogues Gallery"
Not just Joker and Riddler but Reeves’ film hinted at quite a few other villains who could emerge in The Batman 2, including Hush, one of Batman’s greatest enemies.