I\'m running Xcode 11.0 on macOS Mojave (10.14.6) and though the iPhone SE is officially supported on iOS 13, it doesn\'t appear in the list of simulators.
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Also can be useful. The problem may be in your project preferences. If downloading simulators didn't work, try this. Open you project in Xcode -> Choose your project on the Navigator which is on the left side Navigator
Then in the Deployment Info in target tab choose IOS version for your project (choose 10 or 11 for all simulator displaying)
Deployment Info