You need to follow this documentation to update your React Native version: https://reactnative.dev/docs/upgrading#react-native-cli
Step 1: Run command
npx react-native upgrade
Step 2: Copy dependencies modules bellow into dependencies property of your package.json file
Step 3: Run yarn or npm install command on your project folder. yarn is recommended.
Step4: Edit build.gradle file on android folder to change minSdkVersion value to 21
Step 5: Run the following comment from your project folder to update CocoaPods
cd ios pod install cd ..
Step 6: Copy App.js file, react-native.config.js file, src folder and assets folder from Source Code folder to your project folder.