It's often said that flatbeds don't have the required resolution for 35m negatives. In this video I compared an Epson flatbed scanner to a plustek 8200i to see how big the difference was and wether or not it was possible to approximate the plustek result with careful adjustment of the Epson file.
Blog post with full size pictures: https://jonathannotley.com/blog-content/2018/1/25/flatbed-scanning-and-35mm-film