After practicing the PUA (Pick up artist) methods, you will certainly become far more confident as a person. This is because you will know for sure that when it comes to girls, what works and what doesn’t. And just in case at some point, your PUA methods do fail, you will know that there is some room for uncertainty always there.
All in all, yes you will become more confident. However, never use these methods with the intention of exploiting someone either emotionally or sexually, as that is what makes you the bad person. Instead, stay true to yourself and to others, and you are all good.