Can I ask if the mc is OP?

In a way, he is

not really, he seems like he is but he got weaknesses too. like the languange of dragon got its side effect, his anti magic is because of his efforts to learn magic. not to mention he is unable to get higher circle of magic. so he is not OP, merely he is smart and knows what his limits are, what his strengths are, and how to use them to full potential. i like how this webtoon is showing how to make full use of what u have and not to have lingering thoughts on what you wont ever have.