For stored files uploading with Zotero file syncing, a future version of Zotero will offer options to automatically delete local versions of files once they're uploaded to save space locally when using download-as-needed mode.
For linked files stored in Google Drive (e.g., using the ZotFile plugin), clearing local copies would be something you'd have to manage yourself, but Zotero wouldn't be able to trigger a download automatically. (It can do that for evicted files stored in iCloud on Macs, though.)
For stored files uploading with Zotero file syncing, a future version of Zotero will offer options to automatically delete local versions of files once they're uploaded to save space locally when using download-as-needed mode.
For linked files stored in Google Drive (e.g., using the ZotFile plugin), clearing local copies would be something you'd have to manage yourself, but Zotero wouldn't be able to trigger a download automatically. (It can do that for evicted files stored in iCloud on Macs, though.)