In an interview with the developers of Samurai Warriors 5, they stated that they currently do not have any plans to implement additional characters to the roster of the game through DLC. Additionally, the developers mentioned that if Samurai Warriors 5 performs well, they would like to create a sequel title. [Thanks, ryokutya2089!]
While there are no plans to add additional characters to Samurai Warriors 5 through DLC, a season pass for the game is planned. Those who purchase the season pass will receive bonus items to power up their characters and gold to enhance or purchase weapons. Additionally, the season pass will come with a total of six additional scenarios, six background music tracks, additional weapons, and horses.
As for a potential sequel, if Samurai Warriors 5 does well the developers would like the next installment in the franchise to star Hideyoshi Toyotomi. Hideyoshi, along with other notable figures of the Sengoku Period, are playable characters in Samurai Warriors 5. This includes Yasuke, Oichi, and Azai Nagamasa.
Samurai Warriors 5 will release for the Nintendo Switch, PlayStation 4, Xbox One, and PC via Steam. The Japanese release date is June 24, 2021 for the Switch and PS4, while the overseas version will release on all platforms on July 27, 2021.