Just as an example:

https://www.apple.com/icloud/find-my/

"Some devices can still send their location for up to 24 hours after they’ve been turned off or have low battery life."

https://www.91mobiles.com/hub/exclusive-google-find-my-device-feature-phone-off

"Google began rolling out this feature as “Powered Off Finding” with the Pixel 8 series, letting users locate their phone even when it’s switched off by keeping the Bluetooth chip active."

And those are only some of the official known possibilities