No “Configure Selection Menu” option
SkySafari Pro 8.1.1 iPhone 13, iOS 26.6.2, iPad Air iOS 26.6.1
Help menu says:
You can also add the "Graph" option to the Tap & Hold object select menu. You can turn this option on or off using the "Configure Selection Menu" under Settings > Appearance & Behavior.
but this setting does not exist.