On the Canon EF-S 18-55mm f/3.5-5.6 III (the non-STM version), manually turning the focus ring while AF is engaged is not recommended because it does not have full-time manual focus override. If damage were to happen, it would most likely be to the lens’s focus mechanism or motor, not the camera body.

That said, a brief turn of the ring does not automatically mean the lens is damaged. The main symptom to check is autofocus performance: test AF on both near and distant subjects and confirm that focus locks normally and images are actually sharp. If autofocus still works consistently, the lens is probably fine.

If this were the STM version, manual input in AF mode is generally less of a concern because those lenses use a different focus system. But for the EF-S 18-55mm III, avoid turning the ring in AF mode in the future.