The Simulator you are trying in command might not be available in your simulators list.
You can check the list of simulators list with the command:
xcrun simctl list
Also, you can start the simulator from the list with command without opening the xcode like:
xcrun simctl boot 4050BA57-C65E-4EDD-9CB3-38AAA9379912
4050BA57-C65E-4EDD-9CB3-38AAA9379912 is the UUID of the simulator you will get it from list.
With React Native to change the default simulator you can try to change the value of --simulator
option from node-modules/react-native/local-cli/runIOS.js
file
It will be by default like this:
{
command: '--simulator [string]',
description: 'Explicitly set simulator to use',
default: 'iPhone Xʀ',
}
You can change that iPhone Xʀ to your required simulator.
As you are making these changes inside the node-modules
it might get changed or affected after npm or yarn install
.