I meant if I purchased a Tesla vehicle through a third party dealership and have it inspected by Tesla themselves before final purchase.
Nope, still can't get warranty added. The only way to get warranty that goes beyond the original is to get a CPO from Tesla. You can have Tesla do the inspection but that's just checking the car.
Now if it's a private sale and they qualify for extending their warranty (<4 years, <50k miles, did annual services) then you can have them add the extended warranty (4 years, 50k miles) then sell you the car. I don't believe there's any to extend the warranty if it's from a dealer, only the original owner can do the warranty extension.