It includes around 20 hours of brand new gameplay, comprising new factions, quests, voiced NPCs, weapons, armour, and pretty much everything else you’d expect from an official DLC packet. Outcasts and Remnats is perhaps the most popular and well-regarded for Fallout 4. Over the years and across many Bethesda games, some especially ambitious modders have taken it upon themselves to develop entire DLC-sized campaign mods.
Download this absolutely massive mod here.