Using expo to build react Native app:
install expo-cli: sudo npm install -g expo-cli
create app: npx create-expo-app sample_project
change directory: cd sample_project
run the app: npx expo start
scan the QR code that is generated and make sure the phone and pc are on same network
Running app using emulator
install android studio and a emulator, and open it.
run your app : npx expo start
then press a to run on emulator, it will install expo Go app in the emulator, and run the app.