Fallout 76 has crafting much like Fallout 4 and works in a lot of the same ways. The biggest difference is crafting will be one of your go too systems in the game and for this reason, it has had a bit of a improvement.
Much like the previous game you can craft weapons, ammo, food, armour and other items like stacks of components. You craft by using the different Junk you can find while exploring Appalachia and these are then broken down into base components which can then make you a new shiny weapon.
The biggest difference to crafting compared to Fallout 4 is that in Fallout 76 you will only start off with a couple of basic items and need to learn new items which you can do so in a couple of ways. Cooking recipes and plans for items can be found not through levelling up but in following ways:
You are able to modify weapons as well through the various crafting stations which will help you improve items for the next time you are in combat. This will allow you to add things like scopes to weapons or resistances or buffs to armour pieces. Mods are usually learned by scrapping weapons or armour you find but you can also buy mods to attach to items.
C.A.M.P crafting items such as walls, turrets, power armour station etc need to be found as well to be able to build more of your base up. You start out with a few basic recipes can expand your range but completing quests or finding plans.