There were film isnerts made to convert plate holders to use film. I use them in my 9x12 cm) cameras but I've nearly finished an adaptor plate to use modern 5x4 film holders in my Houghtons Duchess half plate camera, and I made a similar converter to fit a roll folm back on my Houghtons Victo quarter plate but that's a different approach.

Essentially a film adaptor is a thin metal sheet with three folded lips that hold the film, and then fit like a plate, these are the reason that film is a fraction smaller than the actual plate sizes even today.

Some use a drop of honey to stick film to backing in adhoc plate adaptors

Ian