Here is the full list of all 43 Mafia: Definitive Edition achievements. It takes around 20-25 hours to unlock all of the achievements on Windows.
Completed "The Death of Art"
Completed the game on Easy, Medium, or Hard difficulty
Paid a fine to the Lost Heaven Police Department
Found a copy of Gangsters Monthly
Completed "Moonlighting"
Completed "Just For Relaxation"
Completed "Election Campaign"
Lost the cops after accruing a five star police chase
Found a Mystery Fox
Completed "Crème de la Crème"
Completed "You Lucky ..."
Completed "Happy Birthday"
Completed "Bon Appétit"
Completed "Great Deal"
Completed "Visiting Rich People"
Completed "Omerta"
Completed "A Trip to the Country"
Collected 15 vehicles in the Garage
Lockpicked 5 cars on the streets of Lost Heaven and environs
Completed "The Saint and the Sinner"
Completed "Better Get Used to It"
Completed "Sarah"
Completed "Fair Play"
Took Paulie to a Place of Disrepute
Won the race
Completed "Ordinary Routine"
Completed "Molotov Party"
Found a Pulp Magazine
Found a 'Gangsters of the United States' cigarette card
Completed "Running Man"
Completed "An Offer You Can't Refuse"
Resisted arrest by the Lost Heaven Police Department
Reached 50mph while driving the Bolt Ace
Performed a wheelie for 3 seconds
Collected 30 vehicles in the Garage
Found all Pulp Magazines
Found all copies of Gangsters Monthly
Found all 'Gangsters of the United States' cigarette cards
Found a hidden car
Found all of the hidden cars
Found all Mystery Foxes
Completed the Collection
Completed the game on Classic difficulty