Hey there, just create a simulator build with exp build:ios -t simulator and then run it on iPad Simulator. You can change Simulator device type under Hardware → Device when using the Simulator app.
supportsTablet: false sounds like it’s doing what it’s designed to do - your app isn’t expanding to the iPad viewport and is instead rendering at 2x on iPads. If you want your app to use the full width of the iPad screen, use supportsTablet: true.