A source told Forbes several months ago about who might be in the movie. Among those potentially appearing are Penguin, Riddler, Catwoman, Alfred and Commissioner Gordon. However, the article also reveals Robin might play a role in Reeves' upcoming film. The language of the report is tentative, so it's entirely possible this will prove untrue, especially considering how many iterations the script is rumored to have gone through.
If the character does have a role, there's no telling at this time just which version of Robin might appear. However, the DC Extended Universe has made reference to one Boy Wonder in previous films. Director Zack Snyder's Batman v Superman featured a Robin costume spray-painted with the words "HAHAHA Joke's on you Batman" in the Batcave. Warner Bros. later confirmed the suit belonged to Jason Todd, evoking the 1988 DC comics storyline "A Death in the Family," in which the second Robin was murdered by The Joker. A report from 2018 indicated Reeves' The Batman wouldn't deal with that death, but the script has undergone a number of rewrites since then, so it's possible that has changed.
Warner Bros. reportedly wants Pattinson to play Batman across three films, so it's possible that, if Robin doesn't appear in the first movie in the trilogy, he might appear in a later one.
The Batman is directed by Matt Reeves, who will also produce alongside Dylan Clark. The film is scheduled to be released on June 25, 2021.