I have a Pixel 7a on the latest version (Android 17, July 2026 build), and I'm able to turn this off. If you want to find it the long way, then tap through the following screens:

  Settings > Security & Privacy > Lost device protection > Theft protection > Theft Detection Lock > (Off)

Or if you want to find it the fast way, open the Settings app, search for "theft", and then tap the first result and turn it off.