Afaik the plasma rifle simply fires in a straight line from the rifle in 3rd person. In 1st person view the plasma beam is also going in a straight line slightly offset from the center. It is lerped to the center path in the first few frames after it is fired to line up both with the 3rd person gun and the final trajectory.
So the position of the gun in 1st person view is false but you are tricked to think it is in the right spot by the muzzle effect.
Other times the recoil effect make the 1st person gun jump to the center when shooting so you don’t have to tweak the muzzle/trail effect in 1st person view
There is many ways to trick the player. The more realistic shooters tend to force you to aim from the center of the screen or hip-fire with no real accuracy.
Physically turning the gun depending on how far the target is seems like an odd solution but I guess some games have tried that too.