It's unfortunate, but there is not an option to Add Service Reference for VB.Net beyond .Net5.0. Furthermore, Microsoft has dropped web development for VB.Net VB.NET support for ASP.NET 5 (MVC6). In Visual Studio, you can only add WCF service references in C# for Net8.0.

https://learn.microsoft.com/en-us/dotnet/core/additional-tools/wcf-web-service-reference-guide