I have not tested this as I don't need a Focus to turn on and off based on my location, but I did find this in a Google AI Search, which may help you (if it is correct?).
"Configure Focus modes to automatically turn on or off based on your location
To set this up, navigate to Settings > Focus, select the desired profile (e.g., Work or Personal), and tap Add Schedule.
Under the location options, you can specify an address or place to trigger the focus mode when you arrive or leave.
Key capabilities include:
- Automatic Activation: The focus mode activates when you enter or exit a specific geographic area.
- Cross-Device Sync: These settings apply across all Apple devices signed into your Apple ID, provided Share Across Devices is enabled.
- Customization: You can further tailor which apps are allowed or silenced within the focus profile to manage notifications precisely."
Again, I don't know if this will work or not, but it's worth a shot.