Is this a viewmodel? or just a script that makes the arms follow where you are looking?

Is this a custom viewmodel, where they just made everything but the arms transparent and then made their own arms that follow where they are looking?

It’s hard to tell. A lot of games use both approaches, each have their own advantages. I’d expect it moreso to be the latter option, but couldn’t say for sure without being in the game or seeing how other player characters look.