I suppose pressing may help getting rid of soft creases but I haven't experimented myself. Plastic will probably respond better to pressing than paper notes. However, hard creases are permanent, and pressing will most likely not improve the look of such notes.
Since polymer currency is only 20 years old, there are no issues or varieties that are impossible to find, and the prices are reasonable. This said, there is no reason in going through the trouble of improving the appearance of notes.