Yes. ISO 400 film tends to be very grainy when enlarged.
Toi make enlargements over 8x10 with 35mm, you need ISO 50-100 film and a tripod, preferably.
That being said, it depends on how you are going to display the print, the viewing distance (ie will viewers be holding it in their hand, or 10 feet away), and other factors. A picture that looks terrible close up may be perfectly fine hanging on a wall viewed from 5-8 feet away.
It all depends on what your goal is. Ive done Mural off 35mm 6' by 4' of course they are grainy but it was about the impact of a large print and not about the image quality. Id say there are no limits.