If you want DNG files in Lightroom CC then it will be necessary for you to convert them first and then add them. You can use the free standalone DNG converter to do that. There isn't a way to create smart previews from within Lightroom CC. I don't see a purpose for doing that from Lightroom CC. If you want smart previews in Lightroom CC then import the images to Lightroom Classic CC and create a collection to share on Lightroom CC. My collection that is shared will be a collection of smart previews.
Thanks for the answer. My reason for wanting to convert to DNG in Lightroom CC is to add to my main catalog remotely. Were I to use lightroom classic to import on my laptop, I wouldn't be able to sync the new files to my adobe account without overwriting the existing Lightroom Classic catalog I have synced from my desktop :
And there is no room on my laptop to fit a copy of my entire desktop catalog.
In any case, I can just import the original RAW files to LR CC and convert to DNG on my desktop retroactively.
One possible workaround would be to use the DNG converter to convert the raw files direct from the camera card with the destination being a flash drive. Then you could import into Lightroom CC from the flash drive. Just a thought, maybe it won't work the way you would want it to.
That sounds workable -- thanks!