#Qute

I have the same problem, OS Sierra trying to run iPhone SE with 10.3 using Xcode 9.2 and I don't have the resources to update to High Sierra and Xcode 9.3.

#Solution:

1.Find your friends who have Xcode 9.3(higher version fits your iOS version)

2.Ask them to right click on Xcode, Show Package Contents then navigate to Contents/Developer/Platforms/iPhoneOS.platform/DeviceSupport/11.3 (15E217)

Copy the 11.3 (15E217) folder to your old Xcode (9.2) with the same file hierarchy

Now you have Xcode 9.2 with iOS 11.3.

#cite:

Xcode not supported for iOS 11.3 by Xcode 9.2 needed 9.3 - Stack Overflow