Pat the roast dry. Season all over with salt, pepper, and garlic powder.
Set Instant Pot to Sauté. Heat olive oil until shimmering.
Sear the roast 3–4 minutes per side until browned. Cancel Sauté.
Pour in beef broth. Scrape up browned bits with a wooden spoon.
Whisk in tomato paste, Worcestershire, soy sauce, thyme, and rosemary.
Scatter onions around the roast. Pile carrots and potatoes on top.
Lock lid and set to Pressure Cook on High for 60 minutes.
Let pressure release naturally for 10 minutes, then quick release any remaining steam.
Transfer roast and vegetables to a platter and tent with foil.
Return pot to Sauté. Stir together cornstarch and water. Whisk slurry into the cooking liquid and simmer until thickened.
Slice or shred the beef. Serve with vegetables and plenty of gravy.