Add the French onion soup, beef broth, onion, garlic, and pepper to the Instant Pot.
Slice the beef roast into 3 pieces, then add to the Instant Pot. (This helps to reduce the cooking time.)
Place the lid on the Instant Pot and lock it. Make sure the lever is set to seal. Select the "pressure cook" button and set the time for 60 minutes.
Let the pressure release naturally for 30 minutes. Remove the lid and shred the beef with a fork. If you are making a sandwich add 3 ounces of beef to bread and serve with 1/4 cup of the au jus.