In the end, Kratos traps them in a mirror and breaks it, so they're most likely dead or trapped in the glass ... Magni, the eldest son of Thor, was a bit more favored than Modi in their father's ...

One fan pointed out, “Kratos literally flipped the nine realms, killed Greek gods and the Titans, killed someone with precognition, and killed Thor and his sons.” It’s hard to ignore that ...