Currently, the auto-create option ("Create referenced entities if they don't already exist") only allows for taxonomy terms. I think this should be available for other entities as it is with the entity autocomplete within core.
I've seen that Drupal\Core\Entity\Plugin\EntityReferenceSelection\DefaultSelection allows for other entity types but then WebformEntityReferenceTrait unsets the form elements (auto_create and auto_create_bundle) when it's not dealing with a taxonomy term.
Remove the restriction. I know that simply updating the condition within WebformEntityReferenceTrait will not be the only change required but with some guidance on this I could create a patch with this change and any further changes. I've tried removing the restriction within Drupal\Core\Entity\Element\EntityAutocomplete but the $element['#autocreate'] is always NULL so the selection settings don't seem to be getting passed through correctly. If I force $autocreate to be TRUE then the entity is created.
Closed: won't fix
6.2
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I don't want to support auto create for other entities. It is going to create question and issue for users.
this is a use we use too. We regularly have need to create a new entity reference in a webform that is not a term. It's no more 'confusing' for users than many other aspects of drupal imho.