It was announced that [Oshi no Ko] would be receiving a third television anime season. At this time, there is no premiere date or information; however, a teaser trailer was shown which you can check out below:
As for the manga, the official announcement for the manga’s end was revealed to be October 24. This means that the manga only has four chapters left (as of the time of this writing) before it concludes. The final chapter will release in the 50th issue of Weekly Young Jump which is set to go on sale in Japan on November 14.
The final tankoban will release in Japan on December 18.
Source: Crunchyroll