Thank you for contacting us.
Native Advanced ad format is currently in beta release to a limited group of publishers. It could be the reason of why you're not seeing them while creating new Ad Unit IDs. If you're interested to participate in the Native Advanced beta release, you will have to reach out to your Technical account manager. If you do not have a technical account manager, you can contact the
AdMob Product Support team and they will be able to assist you one. You can contact the AdMob Product Team through the Contact Us button on the upper right corner of
this page.