Hi @mayank_singh
I am assuming that the URL shortening is handled by SMS vendor unless there is any custom implementation done as Adobe Campaign does not have inbuilt URL shortening function.
Talking about web app link. Every web app link with Preloading have below format:
<https_Web_App_Url>?id=<%= escapeUrl(cryptString(recipient.id)) %>
Generally, all SMS vendors detect the link using https and short the complete URL.