Yes, you will have to amend the 2018 tax return to add the 2018 W-2's
See this TurboTax support FAQ for amending a 2018 tax return - https://ttlc.intuit.com/community/amending/help/how-do-i-amend-a-return-in-turbotax/01/27579
If you have not received a CP-200 letter from the IRS notifying you of the mismatch from what your employers reported for your W-2s and your not reporting the W-2s then you should file an amended return.
This link How to amend (change or correct) a return you already filed provides information on how to amend your tax return.
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