Thanks everyone!

Yes @gururajkoni69, I checked this document already. That's the reason I wanted to confirm.I found a couple of articles pointing the custom implementation for this like https://github.com/nateyolles/aem-clientlib-async.This is being mentioned here in this post as well:https://experienceleaguecommuni...

I would like to know if it is ok to use defer=true parameter to clientlibs without any custom implementation? Using AEM 6.5.16