I already have it so that the player can rotate relative to their movement whilst the cursor is locked to the center screen. Here's the code for that in case it is needed.

local Players = game:GetService("Players")
local ContextActionService = game:GetService("ContextActionService")
local UserInputService = game:GetService("UserInputService")
local RunService = game:GetService("RunService")
	 
local camera = workspace.CurrentCamera
local cameraOffset = Vector3.new(2, 2, 5)
local player = Players.LocalPlayer
 
player.CharacterAdded:Connect(function(character)
 
	local humanoid = character:WaitForChild("Humanoid")
	local rootPart = character:WaitForChild("HumanoidRootPart")
	humanoid.AutoRotate = true
 
	local cameraAngleX = 0
	local cameraAngleY = 0
 
	local function playerInput(actionName, inputState, inputObject)
		-- Calculate camera/player rotation on input change
		if inputState == Enum.UserInputState.Change then
			cameraAngleX = cameraAngleX - inputObject.Delta.X
			-- Reduce vertical mouse/touch sensitivity and clamp vertical axis
			cameraAngleY = math.clamp(cameraAngleY-inputObject.Delta.Y*0.4, -75, 75)
			-- Rotate root part CFrame by X delta
			
		end
	end
	ContextActionService:BindAction("PlayerInput", playerInput, false, Enum.UserInputType.MouseMovement, Enum.UserInputType.Touch)
 
	RunService.RenderStepped:Connect(function()
		if camera.CameraType ~= Enum.CameraType.Scriptable then
			camera.CameraType = Enum.CameraType.Scriptable
		end
		local startCFrame = CFrame.new((rootPart.CFrame.Position)) * CFrame.Angles(0, math.rad(cameraAngleX), 0) * CFrame.Angles(math.rad(cameraAngleY), 0, 0)
		local cameraCFrame = startCFrame:ToWorldSpace(CFrame.new(cameraOffset.X, cameraOffset.Y, cameraOffset.Z))
		local cameraFocus = startCFrame:ToWorldSpace(CFrame.new(cameraOffset.X, cameraOffset.Y, -10000))
		camera.CFrame = CFrame.new(cameraCFrame.Position, cameraFocus.Position)
	end)
end)
 
local function focusControl(actionName, inputState, inputObject)
	-- Lock and hide mouse icon on input began
	if inputState == Enum.UserInputState.Begin then
		UserInputService.MouseBehavior = Enum.MouseBehavior.LockCenter
		UserInputService.MouseIconEnabled = true
		ContextActionService:UnbindAction("FocusControl", focusControl, false, Enum.UserInputType.MouseButton1, Enum.UserInputType.Touch, Enum.UserInputType.Focus)
	end
end
ContextActionService:BindAction("FocusControl", focusControl, false, Enum.UserInputType.MouseButton1, Enum.UserInputType.Touch, Enum.UserInputType.Focus)
Anonymous