The piece you may be missing, is that when you say yes, ATC comes back with, “cleared to the XYZ airport…”. Once you have your IFR clearance you are no longer VFR. You are IFR.I had answered "affirmative" and she responded "cleared to XXX upon reaching 3900'" would I legally have been able to climb into IMC to 3900' ? Seems like I'm still under VFR rules until reaching 3900' which includes maintaining VFR cloud clearances