Preheat Instant Pot to saute setting. Add olive oil and butter and swirl to coat. Add pancetta, pork, and beef. Season generously with salt and pepper. Cook, stirring occasionally, until liquid evaporates from meat and begins to brown, about 10 minutes. Add onion, carrots, celery, garlic, tomato paste, fennel seeds, red pepper flakes, and thyme sprigs. Season with salt and pepper and cook until softened, about 5 minutes.
Add red wine and cook until reduced by three-fourths, about 6 minutes. Add chopped tomatoes, stir to combine, and season to taste with salt and pepper before topping with lid. Set pressure to high and cook 35 minutes before releasing pressure naturally for 10 minutes. Release pressure automatically. Open lid and return Instant Pot to saute setting. Add heavy cream and stir to combine. Cook until slightly reduced, stirring frequently, about 15 minutes more. Season to taste with salt and pepper and use as desired.