I sold my 2018 Raptor with an MPT tune in April to a local dealer in Houston who bought it for more than I paid for it new. I gave the dealer my tuner with all three tunes and the factory tune loaded on it. I sure hope they passed it on to the new owner.
As others have stated, if you call the common Raptor tuners with your VIN, they require the factory tune when you order new tunes, so they should be able to locate yours in their files. You will need to buy a physical tuner, but they should give your your factory tune for free and they might even include the tunes that were originally bought for your truck.
I confirmed you did not buy my truck by checking the VIN posted previously against mine, as I still have my factory tune stored on my computer.