I am going to be up converting my amateur film to 4k and want to add grain to it. I want it to look like professional cinematic grain and was wondering what settings anyone might recommend to achieve either a 35mm look or a 16mm look. Thank you in advance! 
For the most control over the grain look, I would recommend using tools in a traditional editing app like Premiere or Resolve which gives more options and overlays.
However, in Topaz Video you can choose from three options under the Grain feature. Here is a link to the docs page that goes over them and how they can be used. Depending on your source video, I would try the Gaussian or Silver Rich first and see how they work on your video and then increase or decrease the settings for amount, size and density.
