What are Appium Desired Capabilities for the IOS platform?

Desire Capabilities for iOS when you have your .ipa/.app file with you:-

{ 
    "platformName": "iOS", 
    "platformVersion": "11.0", 
    "deviceName": "iPhone 7", 
    "automationName": "XCUITest", 
    "app": "/path/to/my.app" 
}

Desired capabilities when you know bundleID and want to launch existing app

{
  "udid": "af9f8cec090145c64e092f3339fe2f59d832c722",
  "deviceName": "Iphone (12.1)",
  "automationName": "XCUITest",
  "bundleId": "com.pb.education",
  "platformName": "iOS"
}

There are other capabilities if you want to launch app using your code these are udid, xcodeOrgId and xcodeSigningId. You can find complete list of desired capabilities in first link of Related Section mentioned below.