Not directly. Apple Photos is the bridge between your Lightroom exports and iCloud Photos.
There is no direct Lightroom Classic → iCloud Photos sync
Lightroom Classic manages your catalogue and local files. Apple Photos manages its own library. To put a Lightroom edit into iCloud Photos, first export the image and import it into Apple Photos on your Mac.
You can do those steps manually, or use a publish plugin such as LR to Photos. Once the image is in the appropriate Photos library, Apple handles iCloud syncing.
iCloud Drive is different
Exporting a JPEG to an iCloud Drive folder stores a file in iCloud Drive. It does not add that file to iCloud Photos. You still need to import it into Photos if you want it in the Photos app’s library.
The System Photo Library matters
A Mac can have multiple Photos libraries, but iCloud Photos is available only for the System Photo Library. A separate local library is useful for a demo, but its contents will not appear on your iPhone through iCloud Photos. Apple explains the System Photo Library.
Changing which library is the System Photo Library affects your iCloud setup. Follow Apple’s guidance and keep backups before making that change.
Adobe cloud sync is another route
Lightroom Classic can sync selected collections with Adobe’s cloud for access in the Lightroom app. Classic uploads Smart Previews that do not count against your Adobe cloud storage quota. This does not automatically populate Apple Photos. Read Adobe’s sync FAQ.
The practical workflow
Edit in Lightroom Classic → export or publish into Apple Photos → let iCloud Photos sync to your devices.
For a one-off transfer, follow our manual export guide. For a repeatable collection workflow, see how to set up LR to Photos.