Rotate screen on ipad
Fix screen from portrait to landscape
iPad Pro 11-inch Wi-Fi
Swipe a finger down from the upper right hand side of your iPad’s screen to reveal the iOS/iPadOS Control Centre, and tap the icon/button with white background and red circular arrow with padlock symbol inside to unlock the iPad rotation lock.
Be advised, many iPhone apps do not rotate on an iPad.
Best of Luck to You!