In Fallout 76 there is only 1 difficulty level so it can not be adjusted. Unlike previous Fallout titles, your character's levels do not affect the Hit Points, only the endurance will. Your health point will be 250+(Endurance×5). However, to improve the gaming experience and prevent the griefing seen in games like Rust and DayZ.
Fallout 76 Difficulty Modes
Players will be given the ability to swap in and out between players-versus-players and players-versus-environment, as they choose. As it describes, PVP's purpose is to fight other players so there won't be a lot of consequences in regards to killing others but balance changes may be implemented to prevent a one-sided battle. Upon death, players can rejoin the battle by selecting a spawn location on the map, losing a few scraps (used to craft weapon mods etc) where they died.
In PvP mode, the caps you can acquire from killing another player is depending on their levels. Therefore a low-level player is a less desirable target. Players are also protected by the murder system. Which, according to Bethesda's Todd Howard, when you initially attack someone, you'll deal greatly reduced damage until they return fire.
If you attack someone who doesn't fight back and kill them, you not only won't receive any caps, you'll also be marked as a wanted murderer. While marked, you won't see other players on the map and you'll appear as a big red target on the map to other players. You'll also have a bounty placed on your head, and if someone kills you, that bounty will be taken out of your caps. It's a pretty severe punishment, though it does make me wonder what happens if you're already out of caps when you go on a killing spree. And if you're wondering: yes, you can kill your friend if they become a murderer, even if they're in your party.
You will have a passive buff called pacifist as one final layer of insurance. Pacifist lasts until you reach level five, and as long as you have it you're totally immune to other players. They can't damage you and you can't damage them. This gives new players a grace period to gear up and learns the game mechanics, but once you reach level five, you lose the Pacifist buff and become fair game under the rules of the murder system.
In PVE a bounty system is being set in place to avoid continuous grieving behavior, that encourages players to attack those who do most of the killing. Help including disallowing killing low-level players in PVE to prevent spawn-trapping. The main focus of the game will be the PVE gameplay as there are a wide range of beasts, mutants, and West Virginian Cryptids, running amuck. The landscape can also be altered by finding the different fallout bunkers and nuclear launch codes scattered across the map, and using them to launch more missiles anywhere on the world. The nuked locations are then completely annihilating the area and increasing the radiation levels at the blast site. This in turn further mutates the beasts and spawns rarer loot in the area.