Using a few paper towels, dab both sides and edges of roast to remove any excess juices. Season with salt and pepper.
Set a 6-quart Instant Pot to 'Saute' and heat 1 tablespoon of olive oil. When the oil is hot, sear both sides of the roast until browned, approximately 4-5 minutes per side.
Remove the roast to a plate and set aside. If needed, add 1/2-1 tablespoon of olive oil to the IP. Add the onions to saute for 2-3 minutes. Add minced garlic and saute 30 seconds, or until fragrant.
Pour beef broth into pot, followed by thyme and rosemary. Using a spatula, scrape along the bottom of the pot to remove any brown bits left from searing and sauteing, making sure to get every bit to prevent getting the 'burn' notification.
Add the roast back to the pot. Pour the Worcestershire sauce overtop. Layer the roast with potatoes.
Season with salt and pepper, to taste.
Place lid on the Instant Pot, closing the steam valve.
Switch the setting to 'manual' mode for 45 minutes on high pressure. When finished cooking, quick-release pressure according to manufacturer's directions.
Add the carrots and mushrooms. Select the 'manual' mode, adjust the pressure to high, and set the time for 10 minutes. When finished, quick-release according to the manufacturer's directions.
Remove vegetables and beef from the IP using a slotted spoon. Shred the beef using two forks. Serve garnished with parsley and drizzled with gravy.