In addition, it is confirmed that Linked Horizon and cinema staff will perform the second half's opening and ending themes, respectively. This isn't the first time these two groups performed themes for the series as Linked Horizon performed the opening theme songs for the show's 1st and 2nd seasons and the ending theme of the first half of the 3rd season, while cinema staff performed the second ending theme of the 1st season.
Attack on Titan Season 3 returns this April on NHK General TV.
[Source: Anime News Network (link 2)]