The Local option of desktop Lightroom isn’t currently available for the mobile versions. Right now, the only way I can think of to achieve your goal is:
1. Before the trip, install the Lightroom app for iPad.
2. In the Lightroom app, pause syncing, and
never enable syncing during the trip.
3. Import and edit as needed.
4. When you get home, do not enable syncing in the Lightroom iPad app if uploading all images will exceed your cloud storage limit. Instead, either re-import directly to Lightroom Classic from the camera cards, or export everything out of the Lightroom app and re-import into Lightroom Classic. If you choose to export from the iPad app:
- If you want to include edits done on the iPad that you can continue to adjust in Lightroom Classic, for File Type select DNG.
- If you want to export the unedited originals, for File Type select Original.
5. After exporting all images from the iPad app, delete all images from the iPad app. This means delete them
and then (very important) go into the Deleted album and then manually permanently delete those. If you do not do this, deleted images will sync when you re-enable sync! (This is to allow recovery of deleted images, but you don’t want them all to sync if that will exceed your cloud storage limit.)
6. After all images are deleted, now it is finally safe to re-enable sync without blowing out your limit.
There must be enough unused internal storage for all of the images you anticipate importing during the trip, because there is no way to avoid using internal iPad storage with this workflow.
If you want a more Lightroom Classic-like workflow on the iPad without depending on the cloud, you might look into the new
Nitro app (not connected to Adobe). You can import, view, and cull images in it on the road, and the big deal is that the originals can be stored normally out in the iPad OS Files app for easy transfer to Lightroom Classic later. But any image edits you do there won’t transfer to Lightroom Classic.