OP:
You DO NOT want to buy a 2019 MacBook Pro if...
- it's a 13" with the butterfly keyboard
- it's a 15" with the butterfly keyboard.
The butterfly keyboard is highly-prone to failure.
And when it fails -- EVEN IF IT'S ONLY ONE KEY -- the ENTIRE top case of the computer has to be replaced.
That's going to cost you $750 or more -- JUST FOR ONE KEY.
Apple currently has an extended warranty on the keyboard, but it's for 4 years from the date of purchase. That means the warranty on a 2019 MBP will run out next year.
Do you really want to take a chance on one of these?
Having said that...
The 2019 MacBook Pro 16" has the improved "scissors style" keyboard.
Completely different design.
That might be a worthwhile buy.
But having said that...
The best place to buy a "used" MBP is from the Apple Refurbished online store.
Then you KNOW what you're getting.