how would i replace a characters appearance with models? (if you can)

so i got some models for the players appearance but i dont know how to make it so the player switches to the appearance.

server

function onPlayerRespawned(newPlayer)
    while true do
        if newPlayer.Character ~= nil then break end
        wait(.5)
    end

-- what do i do here?

end

function onPlayerEntered(newPlayer)
    newPlayer.Changed:connect(function (property)
        if (property == "Character") then
            onPlayerRespawned(newPlayer)
        end
    end)
end

game.Players.PlayerAdded:connect(onPlayerEntered)