How to get rid of scam Apple security shutdown

See >>> Recognize and avoid phishing messages, phony support calls, and other scams - Apple Support

Don’t respond to, or engage with, the message. Certainly do not, under any circumstances, attempt to contact anyone using the contact details that may have been provided. Alerts of this nature are designed to scare the unwary into giving away sensitive information - or to fool you into doing something that you shouldn’t - usually to defraud you financially.

If you are unable to close the associated alert/window, perform a forced restart of your iPad:

Force restart iPad (models with Face ID or with Touch ID in the top button)

If your iPad doesn’t have the Home button, do the following:

1. Press and quickly release the volume button nearest to the top button.
2. Press and quickly release the volume button farthest from the top button.
3. Press and hold the top button.
4. When the Apple logo appears, release the top button.

Force restart iPad (models with the Home button)

Press and hold the top button and the Home button at the same time. When the Apple logo appears, release both buttons.

Is this for ransomware getting into Safari on iPad (different from Lockdown mode)?

1. Force-close the Safari app,
2. Go to Settings﹥Safari﹥Clear History and Website Data﹥[Confirm] All cookies will be lost, including site sign-ins.