If your any reason you don want to link this project using 'react-native link', go to settings.gradle and add
include ':react-native-image-resizer'
project(':react-native-image-resizer').projectDir = new File(rootProject.projectDir, '../node_modules/react-native-image-resizer/android')
then go the file that you build the ReactInstance and add the packager to it.
ReactInstanceManager.Builder builder = ReactInstanceManager.builder()
.setApplication(application)
.setDefaultHardwareBackBtnHandler(application.getGAMActivity())
.setInitialLifecycleState(LifecycleState.RESUMED)
.setCurrentActivity((Activity) application.getGAMActivity())
.addPackage(new RealmReactPackage())
.addPackage(new MainReactPackageWrapper())
.addPackage(new StoreReactNativePackage())
.addPackage(new ImageResizerPackage()) <------- (Add this package on the Builder list)
.addPackage(gamCommunicationReactPackage);