Is there anything a girl can do if the majority of her pubic area including her inner and outer labia and clitoris are saggy and wrinkly?
The texture and look of every woman's genitalia varies from woman to woman. It is the same as hair color, eye color and so on. The simple answer is yes. There are various bleaching creams and surgical procedures that can change a womans genitalia.
The real question is: Why would you want to?
Plastic surgery is not covered by insurance as it is an elective process. Meaning you are choosing to have it, that it is not required. Men and women alike should be comfortable with their bodies. No matter how wrinkled or saggy you may be, it is you and you should embrace your own image.
The basis of this question would seem to stem from the 'asker' having had an unpleasant experience which inspired the thought of changing themselves. You should not change for anyone and anyone who cannot respect you or your body (and everything that comes with it) is not worthy of your time.
Your skin gets wrinkly in water because of the difference in the partial pressures of the salts between your body and the water. Your body absorbs some of the water to attain a balance. In ocean water, your skin doesn't get wrinkly, because ocean water is as salty - sometimes MOE salty - than your body is. So there's no transference.