The ending of Fantastic Beasts: The Secrets of Dumbledore explains itself in three beats: the qilin chooses Vicência Santos, the blood pact breaks, and Grindelwald flees as a free enemy. Spoilers follow.
The living qilin bows to Vicência Santos, so Grindelwald loses his claim to lead the wizarding world, even though the fake qilin had already crowned him. When he tries to kill Credence, Dumbledore and Aberforth protect the young man, and the clashing magic breaks the pact that kept Dumbledore from acting against him. Grindelwald runs, and the two men are now able to face each other. Credence, weak and dying, is taken home by Aberforth.
The last scene is quieter. In New York, Jacob and Queenie marry, with Newt and Tina in the wedding party, and Dumbledore watches from afar before he leaves. In my opinion, that scene is the film's real conclusion for the ensemble, because it gives the Jacob and Queenie thread a warm close while the larger conflict is left open for what comes next.
It could be argued that the broken pact matters more than the election result. The vote is a public contest that Grindelwald loses once the fake qilin is exposed, but the pact was the governing rule of the whole story, and its end removes the reason Dumbledore had to work through Newt's team. Perhaps that is why the film feels more like a Dumbledore chapter than a Newt one.
The franchise's next project is the Harry Potter TV series on HBO, which TODAY reported as set for December 25, 2026. For what is confirmed and what is only rumor, see the new Harry Potter movie page.