How Can I Upload File More Than 4 G Size In C# Asp.Net

First I don't know why you are using sessionState in MVC, note that a good practices dictates that you should consider avoiding them (even before the MVC was introduced).

Nevertheless back to your upload issue, you can modify the project's web.config file to enable the 2GB upload. To be more specific you need to increase the maxRequestLength which is 4096 KB (4 MB) by default and probably the executionTimeout.
Also you need to adjust another restriction of ~28.6 MB for requestLimits.

<system.web>
    ...
    <httpRuntime maxRequestLength="2147483647" executionTimeout="3600" />
	<security>
      <requestFiltering>
        <requestLimits maxAllowedContentLength="2147483647" />
      </requestFiltering>
    </security>
    ...
</system.web>

But for larger uploades you would need to change the approach, you can try some suggestions mentioned here: Upload large file in asp.net mvc[^]
Or you can try this: How to upload a big file in Mvc?[^]