You can choose to have auto adjustment applied when images are imported. Or, you can highlight all the images in a folder, turn on auto-sync, and then check the auto adjustment.
Thank you very much!!
In the Library grid view, left pane, at the top, click on the "previous import" collection.
Select all the images.
In the right pane, Quick Develop panel, Tone Control section, click the "auto tone" button.
How have I went my whole life not knowing this!? It's working like a charm.