Does PC, PS4 and Xbox One crossplay support? No! This is confirmed by the Game Director of Bethesda Game Studios, Todd Howard, in the GameStar interview. The designer legend has also identified a culprit: Sony ! The PlayStation group was “not as helpful as everyone would like it.” Bethesda said she wanted the first multiplayer offshoot in the Fallout series with the number 76 crossplay, because cross-platform gaming is “a big trend in the games industry,” as Todd Howard explains in an interview.
Source: N4G PC Fallout 76 – No Crossplay, because "Sony is not as helpful as everyone would like it to be"