Go to Menu -> Devices -> Meta Quest 3 (make sure it’s connected) -> Headset Settings -> Developer Mode, then turn on developer mode
Now go to your headset Settings -> System -> Developer, and enable custom settings
There you have it!
Now you can enable/disable Quest 3 boundary whenever you want, simply by going to settings.
Disabling Boundaries and Keeping Passthrough
At the moment, you can’t disable boundaries and whilst keeping passthrough mode on. It’s kind of stupid because what’s the point of a guardian boundary when you have passthrough? I’m sure Meta has realized this and will change it in the future.