They do have cross-play, but as far as I know it's opt-in when playing with friends. Matchmaking will usually group you with others playing in a similar way.
Fortnite is now "Skilled-based match making, with forced cross-play". Doesn't matter what platform you are on, you are matched by your relative skill level. High-level 6-finger-claw iPad players (and some of them are really incredible!) will be in lobbies with medium-level console and PC players.
