Both, of what I've played of XV so far, the exposition largely comes through the gameplay, you're hearing it on the radio etc as you're exploring, your party are discussing events and motivations of enemies, their relationship develops slowly like this. There's far from nothing happening in the plot, it's all there if you go looking for it.
You know the game won't continue like that right ?
Come back when you've played the linear part and seen how the game handles its narrative in these parts relative to XIII's linear parts.
Its worse.