Is it possible to make larger/bigger iris?

This is a dangerous, non-FDA approved surgery that is still being performed.  The surgery has proven to be vision threatening.  It does not make the iris bigger.  There are some who have eyelid issues that make the eyes look small.  Posting a photograph might help resolve that issue.  Some individuals do get oversized contact lens to make the eyes look like anime eyes.  It is a bit freakish but under direct medical supervision, this is a possible option for you but you need to work with a licensed contact lens specialist who is either an optometrist or and ophthalmologist.