Fallout 76 is set decades before the other Fallout games, but that doesn't mean you're safe from Preston Garvey, the settlement-obsessed dork from Fallout 4. A Fallout 76 player, RpTheHotrod, is roleplaying Preston, and quite impressively: not only did he use the character creator to design a convincing Preston lookalike, and outfit him with Preston-style clothing, he's playing audio clips from Preston's endless settlement quests over his mic to other players.
In the video below, you can see a few clips of Preston in action, including an encounter with another player decked out in power armor. The other player chuckles as he sees the least popular Minutemen officer standing there. Then, as Preston's voice clip states that a settlement needs help after being overrun by ghouls, the other player sighs "Oh, god."
Finally, he humors Preston. "Where's the settlement at?" he asks in the tired, resigned way we all feel when finally accepting one of Preston's never-ending tasks.
I'm not sure how much further you can take this Preston cosplay: you can build bases in Fallout 76, but there's no settlement system due to the complete lack of settlers. But just approaching other players as Preston and giving them a good laugh (plus a deep sigh) seems pretty damn rewarding in itself. Hopefully we'll see more footage of Preston soon: this Reddit thread is a good place to watch for it.