According to the official Twitter account for the anime Kaguya-sama: Love is War, it will have a third season, as well as an OVA project. The OVA will be released in 2021 .
https://twitter.com/anime_kaguya/status/1320289876248424449
The second season of Kaguya-Sama: Love is War aired on April 11th, and was therefore streamed by Funimation as the episodes were released in Japan.