@karthik-elumalai thank you for posting in Communities. Great place to learn, collaborate. So as per your question, you want to provide aem author link in a third party application and user upon clicking the link directly should login to aem author without further login screen?
Where is the third party application hosted? Please explore the option of using SSO(Single Sign On) which will enable access multiple applications with a single sign on to any application under its configuration.
AEM supports almost any SSO IDPs.
If you are not looking for SSO , please help us with more details..