Cannot find "Lookup Element" in "form page designer"

Hello Community, 

Kind of dummy question, but in the new UI, where is the "lookup element" that can be implemented? In configuration section, contacts are in "custom" package. Did not see a section page referring to contacts, Only form page seems to be valid. Relevant Image that I was expecting to find a custom "lookup element" that can be dragged/dropped is shared.

Thank you in advance!