How can I make a camera similar to the one of Roblox Studio?

You can simply go into ROBLOX studio, and press Left Shift + P to go into "free-cam" mode. From there you can look at the contents of ROBLOX's script.

I just noticed this post, Sorry that it took so long for a proper answer. Anyway, I made what you were wondering about. I edited CloneTrooper1090's NoClip script, and here it is (local ofc)

    -- Basic Freecam Script
    -- You can move faster by holding the click button [setting below ! :) ]
local allowspeedmove = true
wait(1)

local c = workspace.CurrentCamera
local player = game.Players.LocalPlayer
local userInput = game:GetService("UserInputService")
local rs = game:GetService("RunService")
local starterPlayer = game:GetService("StarterPlayer")
--local util = LoadLibrary("RbxUtility")
--local camSync = util.CreateSignal()

local selected = false
local speed = 60
local lastUpdate = 0

local camera = Instance.new('Part', workspace)
camera.CanCollide = false
camera.Anchored = true
camera.Transparency = 1
camera.Name = 'FreeCam'
camera.Position = player.Character.HumanoidRootPart.Position + Vector3.new(0,5,0)
--rs:BindToRenderStep("CamSync",190,function ()
--  camSync:fire()
--end)

c.Changed:connect(function (property)
    if property == "CoordinateFrame" then
--      camSync:fire()
    end
end)

function getNextMovement(deltaTime)
    local nextMove = Vector3.new()
    -- Left/Right
    if userInput:IsKeyDown("A") or userInput:IsKeyDown("Left") then
        nextMove = nextMove + Vector3.new(-1,0,0)
    end
    if userInput:IsKeyDown("D") or userInput:IsKeyDown("Right") then
        nextMove = nextMove + Vector3.new(1,0,0)
    end
    -- Forward/Back
    if userInput:IsKeyDown("W") or userInput:IsKeyDown("Up") then
        nextMove = nextMove + Vector3.new(0,0,-1)
    end
    if userInput:IsKeyDown("S") or userInput:IsKeyDown("Down") then
        nextMove = nextMove + Vector3.new(0,0,1)
    end
    -- Up/Down
    if userInput:IsKeyDown("Space") or userInput:IsKeyDown("Q") then
        nextMove = nextMove + Vector3.new(0,1,0)
    end
    if userInput:IsKeyDown("LeftControl") or userInput:IsKeyDown("E") then
        nextMove = nextMove + Vector3.new(0,-1,0)
    end
    return CFrame.new( nextMove * (speed * deltaTime) )
end

function onSelected()
    local char = player.Character
    if char then
        local root = camera
        currentPos = root.Position
        selected = true
        lastUpdate = tick()
        c.CameraSubject = root
        player.Character.HumanoidRootPart.Anchored = true
        while selected do
            local delta = tick()-lastUpdate
            local look = (c.Focus.p-c.CoordinateFrame.p).unit
            local move = getNextMovement(delta)
            local pos = root.Position
            root.CFrame = CFrame.new(pos,pos+look) * move
            lastUpdate = tick()
            wait(0.01)
        --  camSync:wait()
        end
        player.Character.HumanoidRootPart.Anchored = false
        c.CameraSubject = player.Character.Humanoid
        root.Velocity = Vector3.new()
    end
end

function onDeselected()
    selected = false
end

local isOn = true
spawn(onSelected)

function onKeyPressed(_,state)
    if state == Enum.UserInputState.Begin then
        isOn = not isOn
        if isOn then
            onSelected()
        else
            onDeselected()
        end
    end
end

local mouse = player:GetMouse()
mouse.Button1Down:Connect(function()
    if allowspeedmove then speed = 120 end
end)
mouse.Button1Up:Connect(function()
    speed = 60
end)

function ResetCamera()
    camera.Position = player.Character.HumanoidRootPart.Position + Vector3.new(0,5,0)
end

game:GetService("ContextActionService"):BindAction("Noclip Toggle",onKeyPressed,false,"r")
game:GetService("ContextActionService"):BindAction("Reset Camera Position",ResetCamera,false,"z")

**Yes, I do know you aren't allowed to request things, but I made this anyway, and I wanted to share it with others who may need it. :)