Does anyone know how to set the appearance of the player to a model?

Does anyone know how to edit the appearance of the player? As in you pick a class and your character looks like a robot. I am currently confused as I would have thought the way to do this would be to weld parts to each other and set that as the players character however the player does not seem to have any physical parts in its properties so i have not found any way to replace or set any parts as the player ://

I was wondering if anyone knew how to do this or do you have to basically delete the player and program a brand new model if you want to say be a robot in a game?

Any advice would be greatly appreciated as i am so stuck atm

You can set these properties to the robot like so. This needs to be in a local script. The robot needs a humanoid.

local robot = workspace:WaitForChild('Robot') --Im just pretending the robot is named robot.
game.Players.LocalPlayer.Character = robot
workspace.Camera.CameraSubject = robot:WaitForChild('Humanoid')

Then, the controls should automatically switch to controlling the robot, and the camera should be facing toward the robot.