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.

yarn

npm install

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.