i cant get react native to run ios or android code example

Example 1: react native run specific ios device

react-native run-ios --simulator="iPhone 5s"
react-native run-ios --simulator="iPhone 6"
react-native run-ios --simulator="iPhone 6 Plus"
react-native run-ios --simulator="iPhone 6s"
react-native run-ios --simulator="iPhone 6s Plus"
react-native run-ios --simulator="iPhone 7"
react-native run-ios --simulator="iPhone 7 Plus"
react-native run-ios --simulator="iPhone 8"
react-native run-ios --simulator="iPhone 8 Plus"
react-native run-ios --simulator="iPhone SE"
react-native run-ios --simulator="iPhone X"
react-native run-ios --simulator="iPhone XR"
react-native run-ios --simulator="iPhone Xs"
react-native run-ios --simulator="iPhone Xs Max"
react-native run-ios --simulator="iPad Air"
react-native run-ios --simulator="iPad Air 2"
react-native run-ios --simulator="iPad"
react-native run-ios --simulator="iPad Pro"
react-native run-ios --simulator="iPad Pro"
react-native run-ios --simulator="iPad Pro"
react-native run-ios --simulator="iPad Pro"
react-native run-ios --simulator="iPad"

Example 2: run react native app on android device

#enable debug mode on yur device

$ adb devices
List of devices attached
emulator-5554 offline   # Google emulator
14ed2fcc device         # Physical device

$ npx react-native run-android
Try:
$ react-native run-android --deviceId=14ed2fcc

#use adb reverse
$ adb -s <device name> reverse tcp:8081 tcp:8081

NOTE:
You can also use the React Native CLI to generate and run a Release build
(e.g. npx react-native run-android --variant=release).