Software developer can use System.Web.SessionState.HttpSessionState member IsNewSession which identifies whether this session was just created for the current request. If currently no information is in session state, ASP.NET will not make an effort to track the session or create a session cookie. Instead, the session will be re-created with every request.

C# 8.0 and .NET Core 3.0 – Modern Cross-Platform Development: Build applications with C#, .NET Core, Entity Framework Core, ASP.NET Core, and ML.NET using Visual Studio Code, 4th Edition
ASP.NET Core 3 and Angular 9: Full stack web development with .NET Core 3.1 and Angular 9, 3rd Edition
C# in Depth, 4th Edition