Is it possible to get epicanthoplasty if you have double eyelids?

Based on your photo, you have subtle upper eyelid ptosis (droop). This lowers the eyelids and increases the space between the upper eyelid and the eyebrow, which creates a bit of hollowness there. A subtle ptosis repair will help fill in that hollowness. Alternatively, adding a bit of filler to the lower part of the eyebrow will also increase the fullness, but it would not address the slight droop of the upper eyelid.See an Oculoplastics surgeon that is familiar with both these techniques. 

Not sure if epicanthoplasty would achieve what you are looking for. If you desire more fullness, eyelid filler injection may be an option.

I assure you that almost any surgeon you see will not understand your concern. They may nod their head but you are at profound risk of just getting their surgery.  You have upper eyelid ptosis and lash ptosis.  Normally fixing the ptosis and not addressing the upper eyelid fold will cause the raised eyelid platform to disappear under the upper eyelid fold. A small anchor blepharoplasty would form a hard crease and allow a small strip of platform to be available for the placement of makeup.  I would recommend approach for you.  I am concerned that what really bothers you is your compensatory brow flare and the shadowing of the upper portion of the cornea.  This has to be explicit discussed and explored in a personal consultation. Please be careful what you look for out there.