Does macOS 10.13.4 display 32-bit warnings like the beta versions do?

Solution 1:

Yes, after midnight, April 12, 2018 in the user's local time zone

From Ars Technica's "Apple has begun notifying macOS users of coming 32-bit app incompatibility".

Starting at midnight April 12, 2018 in the user's local time zone, they will see the following message the first time they launch an app that only supports 32-bit in macOS High Sierra 10.13.4:

This app needs to be updated by its developer to improve compatibility.

Along with that message, they'll see a "learn more" link that takes them to Apple's support page on the subject with more information. The support page broadly explains Apple's plans to "eventually" require all Mac software to be 64-bit.