film festival camera size?

just wondering what would be the proper camera size if i was going to submit to a film festival? do i have to work in that size or can i convert it after? thanks for any help!

Are you referring the FOV or resolution? (unless you are doing the anamorphic).
FOV varies based on the resolution. And for the resolution, better contact the film festival for the requirement but it is better to work with the same resolution for the requirement since it can have quality issue if it the animation is done in low res and needs to be scaled up after the final render.