Hello,
Dermatology is one of most popular speciality among doctors.
But you cant opt for dermatology after 12. you need to clear neet and then pass mbbs and then chose dermatology as you specialty in the post graduate studies.

You can use careers360 college predictor to know the colleges you can get at your NEET score;- https://medicine.careers360.com/neet-college-predictor?icn=QnA&ici=qna_answer

Hope this helps