I need help with my stolen iPhone 11 pro

Didn't you use a passcode?

Lost Mode lets you lock your iPhone, iPad, iPod touch, Mac or Apple Watch so that others cannot access your personal information.

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Turn on Lost Mode or lock a device

1. In Find My iPhone on iCloud.com, click All Devices, then select the device you want to put into Lost Mode or lock. ... 
2. Click Lost Mode or Lock.

More items...

Lost Mode exactly does that. Please watch till the end.

Watch this GIF below

Use Lost Mode in Find My iPhone on iCloud.com - Apple ...

Which device was stolen, and iPad or an iPhone 11 Pro. I am assuming that it is the latter in this case.

Regardless, see if the following article can help:

• If your iPhone, iPad, or iPod touch is lost or stolen - Apple Support