You can't change a public app into a team app (or vice-versa). To bypass this limitation, you can create a new app with the metadata of the original app. For more information, see Change an app's distribution.
Add an extension
In this phase, you add extensions to the app. An extension is a feature or capability of an app.
An app can have:
Content extensions that import third-party content, such as photos and illustrations, into Canva.