Combine carrots, vegetable stock, coconut milk, onion, garlic, Thai curry paste, salt and pepper in a multi-functional pressure cooker (such as Instant Pot®). Close and lock the lid. Select high pressure according to manufacturer's instructions; set timer for 15 minutes. Allow 10 to 15 minutes for pressure to build.
Release pressure using the natural-release method according to manufacturer's instructions, 10 to 40 minutes. Unlock and remove lid. Blend soup with an immersion blender until smooth and creamy, about 3 minutes. Serve in bowls and sprinkle with fresh coriander.