Short answer: Yes, of course.

Long answer:

The only way you'll be able to manifest the type of hair you want is to line your energy up with it. The LOA (law of attraction) gives you a match to what you are now, not what you want. You have to be a match to what you want before the LOA can give what you want to you. Take your attention off the negative aspects of having curly hair and focus on how you'll feel once you have straight hair. See your desire as a normal, everyday part of your life right now. Practice the feeling of having straight hair not to make it happen but because it feels good when you do it. Practice the feeling long enough and your desire will come. That's the law.

probably that you would need to know the difference between straight and curly hair first. some people that have straight hair get curl when it is humid outside. we know that hair grow out of you contain your dna. and can be affected by static discharge. making it stand straight. you might also have notice that some time your hair is pulsing. the most easy way would be to talk to a barber maybe he got some product to do the job. outside stuff outside solution. inner stuff inner solution. if you could change the inner it would change the outer. it would be good for you to know thy self much more important then desire about hair type.