Batch straighten horizon

See here for how to auto-level a batch of photos using the Transform panel:

https://community.adobe.com/questions-675/batch-auto-straightening-isn-t-working-961997?postid=3920456#post3920456

Perhaps you can select all the photos and use the sync option in the development. Everything you apply to one photo, will be applied to the others.

If you want images to receive some operation(s) automatically by default, such as horizon straightening: this operation(s) can be saved into a develop preset (checking only the required aspects selectively; the preset can leave all other settings alone).

Then this develop preset can be chosen to apply during import.

Or, this operation can be included in a develop preset which is set to apply as the default processing for this particular camera / file type combination. 

Or, this develop preset can be applied to highlighted images in bulk after the fact.

I would recommend a suitable Upright mode, rather than going for the tool within Crop - probably ‘Level’ if you want to permit horizon levelling only, or could be ‘Auto’ if you also want vertical convergence correction.

In my experience correction will be relatively mild: LRc won’t force it overhard, to the point of being pictorially unnatural. Not unless you choose ‘Full’, which is a special-purpose option IMO.