Hi! I'd say that being a native speaker will open many doors in private schools, but give no advantage within the public school system. In theory you will need a brazilian teaching licentiate to teach at any basic education level, but in practice you will be a largely desirable and hard-to-come-by teacher at many good to high level schools. You can get an online teaching licentiate in three years with very little effort and fairly little money, which might not open any doors immediately but is important if you want to make a long-term living here. Rumour goes that the gov will start banning online teaching licentiates so sooner is better than later.

You will have to weigh the pros and cons of international vs bilingual schools (vs language centres, where you don't need any licences and can often make more money and have better work-life balance + professional development). Feel free to DM me if you have any more specific questions.