If your return has been filed & accepted, you would need to amend your return to add the additional W2.  Amended returns must be mailed.  The IRS suggests you wait until your original return is fully processed (refund received or taxes owed are paid) before you amend.

How to amend (change or correct) a return you already filed

https://ttlc.intuit.com/community/amending/help/how-to-amend-change-or-correct-a-return-you-already-...