Start the project in Development mode

Now for testing we can either you an emulator or in your mobile device (if Android) install Expo App.

Once installed come back to the command prompt and in the project folder run command-:

npm start

You will get something like this-:

Once the Project is up and running scan the QRcode via Expo App(for Android) and Camera (for iOS).
It may be possible that the app does not connect with given QRcode so try the other options in connection (like tunnel, LAN, Local) one always works. Once the phone is connected with development environment, you will see JavaScript bundle compiling and being downloaded on phone.

Once the download completes you can see the project synched to the phone and you can start your development.