I have an NOL from 2018. I uploaded my 2018 return to Turbotax, 2018 prepared & filed by an independent tax accountant. Does the 2018 NOL effect my 2019 return?

If the NOL was not all used up on the 2018 return then there is nothing to carry to the 2019 return ... review the 2018 return to see if you have a carryforward to use.

Maybe.  When the 2018 tax return was filed, the NOL that was created would carry over to 2019.  However, last  month Congress has retroactively changed the laws, so now the default rule is that the NOL is carried back to 2013 UNLESS you file an election to "waive the carryback".

TurboTax does NOT calculate the amount of the NOL and is not NOL-friendly in several other ways.  Because of this and the new retroactive law changes, you may want to have a tax professional do it again this year.