Riot has started teasing Valorant's new Duelist officially, and his abilities icons have also been potentially revealed by them. While they haven't announced the name or abilities of Agent 24, leaks by KLaboratories have revealed that our new duelist will be named ISO; however, no other information was shared.
The new Duelist is expected to be released on October 31 along with Episode 7 Act 3, and based on the teasers by Riot Games, he is a "hitman" and "doesn't miss;" however, keep in mind that this doesn't necessarily mean that Riot will make him an aimbot agent.
Apart from this, other teasers from Riot hint towards the new agent being Chinese, as the name of the image below is "duckblood", which is a popular Chinese dish.
We will update this page once Riot announces the name officially, so make sure to keep an eye on it.