Your iPhone already comes with everything you need to capture amazing photos and video. With a decent vintage camera app, you will be able to capture video just look classic film cameras. Take Super 16 for iOS for instance: it is a 16mm film camera app with over 70 filters for you to play around with.
This app comes with an extensive set of parameters that you can customize to give your footage a unique look. You can change color temperature, brightness, grain level, frame shake, and other aspects of your video. Super 16 lets you change bitrate, resolution, and other settings. It can shoot at 24fps.[where to get it]