https://shopify.dev/api/admin-rest/2022-10/resources/asset#put-themes-theme-id-assets APIs on this page can be used to add extensions to a theme or they only add custom themes?
Hi @YanaDot 
It’s a little unclear what you’re looking to add as part of your extension using the API. I’d recommend reviewing this doc on app integration with online stores that highlight theme app extensions and other integration methods using the Scrip/Asset resources.
Hope that helps!
Hi, once sellers install the app and pass Oauth I want them to have the app blocks activated automatically right away