By default, you use the keyboard hardware of your mac in your iOS simulator. But you may need to test the behavior of the iOS device keyboard when using your react native app. It is also known that React Native has some keyboard-related issues.
Switching from a hardware keyboard to a simulator keyboard is easy.
Open your Simulator >I/O > Keyboard > Toggle Software Keyboard as given in the screenshot below.
You can also prefer the keyboard shortcut command + K to toggle the keyboard.
That’s how you show iPhone simulator keyboard when running react native apps.