CODE EXAMPLE FOR JAVA

react-native force rtl on android

//MainApplication.java
import com.facebook.react.modules.i18nmanager.I18nUtil;

//add this code to the onCreate method 
I18nUtil sharedI18nUtilInstance = I18nUtil.getInstance();
sharedI18nUtilInstance.forceRTL(this,true);
sharedI18nUtilInstance.allowRTL(this, true);