There are a number of different treatments which purport to reduce the size of the labia without surgery. These methods include non-surgical radiofrequency technology. The results vary and are not permanent. If you are looking for a guaranteed way to reduce the size of your labia permanently, then surgery is the only way to achieve this.
There are creams, home remedies and  exercises which claim to reduce labia size. These do not work and we would recommend that you don’t waste your time or money on treatments for which there is very little, if any, scientific proof of their effectiveness.