You could, but it may not be that easy. The age of the film you're trying to replicate has a lot to say about the amount of damage, and the frame rate of the footage should be 23.976 at the very least... and if you're talking REALLY old film, the frame rate could be lower.
As Dave said, while it's possible, it doesn't really make sense. The physical and chemical properties of film stock are affected by so many factors, just having a single look will look weird after a while. Additionally specific creative decisions may affect this further as e.g. dark footage will need stronger noise/ grain to even show. It's really better to tackle this as needed and tweak the effect every time, even if it may result in long extra rendering times in AE.
I think its easy enough with a bit of work.
Create what you want in AEFX as an "organic".....eg scratches , blobs, noise etc.. there are even some presets. to help.
Don't forget you can shoot some stuff to blur and mess up !
...and out put it on a Black BG and also with an alpha.
Both can be useful when you take it to PPro and overlay it using Blend Modes and Opacity