Do you have to compile your apps with Swift6 enabled to ship a production app when iOS18 is released?
Present requirement is
as of April 2024 all iOS and iPadOS apps submitted to the App Store must be built with a minimum of Xcode 15 and the iOS 17 SDK.
Which means Swift 5.9 at least.
Xcode 15.4 uses Swift 5.10 for instance.
I anticipate that it will still be possible to publish from Xcode 15.4.
But what is the problem to fo to Swift 6.0 ? You'll have to do it sooner or later in any case.
Note: don't forget to close your old threads when you've received the correct answer.