Turn the Instant Pot to the sauté setting and brown the pancetta for about 3-5 minutes. Remove and set aside.
Add the olive oil and sauté the onions, garlic and celery for about 3-5 minutes, until softened and starting to lightly brown.
Add the beef, pork and veal and brown, using a spoon to break up any big chunks.
Add the tomato paste and cook for 2 minutes.
Stir in the red wine, using a wooden spoon to scrape any bits off the bottom.
Add the crushed tomatoes, chicken stock, salt, pepper, thyme, oregano, parsley, sugar, crushed red pepper and browned pancetta.
Pressure cook on high for 30 minutes.
Use the quick release to release the pressure then turn the sauté function back on.
Stir in the butter and cream and simmer for 2-3 minutes.
Add additional salt to taste and serve over pasta.