If you want the camera to turn smoothly then that means you need to generate intermediate CFrame using lerping which can be done like so separating position and rotation of a CFrame and lerping the current CFrame rotation towards the goal CFrame rotation.
local camPos = camera.CFrame.Position
local lookVector = planeModel.Body.CFrame.LookVector
local goalCFrame = CFrame.new(camPos,camPos+lookVector)
local lerpToGoalCFrame = camera.CFrame:lerp(goalCFrame,0.25)--0.25 can be anything you want
local rotationOnlyOfLerp = lerpToGoalCFrame-lerpToGoalCFrame.Position
camera.CFrame = CFrame.new(camPos)*rotationOnlyOfLerp