"an IRS assigned PIN" You mean an ID PIN? Yes you would need that in any case (e-file or not).
If you are talking about an e-file pin, then note that the IRS is moving away from the self-assigned e-file pin from 2018 to using your 2018 AGI as the verification.
This should be no problem for you, right?
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If you're asking about the PTIN as opposed to the PIN, you need your 2018 AGI or your 5-digit PIN to e-file your own self-prepared tax return. As for your PTIN, Since Turbotax is for a self-prepared tax return, there's nowhere to enter a PTIN.