Hello Sanchita,

First of all congratulation for your JEE Main score and secondly yes, you can get good government colleges with your EWS rank in JEE Mains. JEE Mains 2019 cutoff for GEN-EWS category is 78.21 percentile , where you got 89 percerntile which means you have qualified as per your category. So you are now eligible to get colleges like NITs,IIITs and GFTIs. But for that you need to attend the JoSAA counselling proccess. Now exactly which particular college or branch you will get that depend on the counselling. If you dont get a good college through JoSAA, then you can apply for CSAB counselling which will begin after the end of JoSAA counselling session. If there is some government college you would like to take admission into through your JEE Main score but the college doesn't participate in JosAA , then you have to attend the respective counselling session for that particular college.
You can go through this link and checkout the detailed information regarding CSAB counselling : https://engineering.careers360.com/articles/csab

Hope you get a good college. Good Luck !!!