Why? Are you a paid tax preparer? If so you cannot use TurboTax to prepare returns for clients. An MEF number is used by paid professional tax preparers.
Or....are you really asking about using ID.me so that you can get the monthly child tax credit payments?
Every e-filed tax return has an MeF Submission ID (SID), even if you filed it yourself with TurboTax and did not use a paid preparer. To get your Submission ID you have to call TurboTax support. Go to the following link for instructions to get a phone number to call, during the hours that support is open. The hours are shown at the link.
If they don't recognize the term Submission ID, tell them it's the "DCN / MeF Submission ID."