I would consider canthopexy together with a conservative brow lift if your main concern is the appearance of the outer eye area. The important first step is to identify exactly what you would like to change, because these procedures affect different structures. Epicanthoplasty changes the skin fold at the inner corner of the eye, near the nose. It is useful when that fold is the specific concern, but it does not address brow position or support at the outer corner. Canthopexy strengthens the support of the outer lower eyelid and may provide a subtle change in its position. It should not be expected to produce a dramatic change in eye shape. A conservative brow lift may complement this if a low outer brow is contributing to the appearance you want to improve. Fat grafting would only be worth adding if there is a hollow area that needs volume. It does not replace the effects of eyelid support or brow repositioning. At 21, I would aim for a subtle result that preserves your natural expression.