Setting up selective sync by file extension

Hello,
Is it possible to only pull .pdf, .doc & .jpg files from cloud to client? We want to give full access to the cloud to a coworker but only want to give them files that contain specific extensions to save space and clutter as out cloud is quite large and most files would be irrelevant.

I was thinking about adding the following pattern to the ignored file field.

^((?!(.pdf|.jpg|.doc)).)*$

Before I do, is there another way to do this? Is this a bad idea?