iOS Simulator version 11 or later is currently not supported.
You can open Xcode > Preferences > Components to download and install an earlier version of the iOS Simulator.
xcode里安装了9.3的simulator
delphi的SDK里怎么找不到，只有11
https://community.embarcadero.com/forum/ui/9390-iphone-x-ios-11-builds-with-rad-studio-10-2-3
等着升级10.3吧