Is there a way to file a 3921 Form from turbotax?

Enter form 3921 in the Search box at the top right of the program screen.  Click on Jump to form 3921

The form 3921 is issued to you by your employer and is purely informational.  The info on the form is used when you sell the underlying stock to support the cost basis figure if the broker has it wrong on the 1099-B.   It is not a supported form in the TT program.