When I am learning the MSAL library, I met some code that use PublicClientApplication.OperatingSystemAccount to get an access token, as shown in this code here:

var publicAppBuilder = PublicClientApplicationBuilder
      .Create(appClientId)
      .WithParentActivityOrWindow(consoleWindowHandleProvider)
      .WithAuthority(authorityUri)
      .WithBrokerPreview(true)
      .WithDefaultRedirectUri()
      .Build();

var result = publicAppBuilder.AcquireTokenSilent(scope, 
   PublicClientApplication.OperatingSystemAccount)
                             .ExecuteAsync().GetAwaiter().GetResult();

The PublicClientApplication documentation also mentioned OperatingSystemAccount as:

A special account value that indicates that the current operating system account should be used to log the user in.

I think the MSAL library code can get the user account from OperatingSystemAccount, and then use that user account to get the access token of the user from Azure AD, is my reasoning correct?