remotely shutting phone down

twothyme wrote:

is it possible to remotely shut down an iphone XR?

No only lock or erasing it If your iPhone or iPad is lost or stolen - Apple Support

No. But if you know the Apple ID it is logged in to go to https://icloud.com/find and you can lock the phone, and do other things such as erase it.

You can put it in lost mode or erase it using Find My.

https://icloud.com/find

It should be encouraging to get 3 answers, and they all agree😏