Kindly refer to the documentation for the appropriate format required for the functionality of smart banners. Additionally, it is straightforward to test the functionality using an internal HTML page before going public.
https://developer.apple.com/documentation/webkit/promoting-apps-with-smart-app-banners#Implement-a-Smart-App-Banner-on-Your-Website
<meta name="apple-itunes-app" content="app-id=myAppStoreID, app-argument=myURL">
Required. Your app’s unique identifier. To find your app ID from App Store Marketing Tools, type the name of your app in the Search field, and select the appropriate country or region and media type. In the results, select your app. In the detail view for your app, find the Content Link. Your app ID is the number between id and ?. Alternatively, select your app in App Store Connect. Under General, select App Information, then find your app ID in the General Information section that opens in the middle of the screen; your app ID is listed as Apple ID.
Optional. A URL that provides context to your native app. If you include the URL and the user has your app installed, they can jump from your website to the corresponding position in your iOS app.
Albert
Worldwide Developer Relations.