Does your Apple ID work on the other phone and the iPad?
Is the Apple ID on the iPhone 11 his ID?
Do you have access to another WiFi network where you can try? That has worked for several people.
Try a restart.
Restart your iPhone, iPad, or iPod touch
Try a forced restart.
Reset Device.
If necessary
Hard reset.
Do a backup and try a factory reset. Then restore from your backup.
Restore to Factory setting.
Backup - Restore your device from an iCloud or iTunes backup.
If necessary, if you are the original owner, contact Apple. Apple can remove the Activation Lock if provided the required paperwork. Either take the device, the original purchase receipt with the serial number, and a photo ID to the nearest Apple Store (if it has reopened)
Genius Bar Reservation and Apple Support Options - Apple.
or contact Apple ID Support.
Apple ID - Official Apple Support.
Contact Apple for help with Apple ID account security - Apple Support. (Link doesn’t always load)
Get Support Work through the screens to get a chat option.
Apple Support schedule phone call
https://twitter.com/AppleSupport People have posted it may take an hour or more to get a response.