If you’re not in the US you will need to make sure Alexa offers location services.
In Alexa app if you haven’t added your home location you’ll need to do that.
Under settings → your location → add your home location.
In phone settings, allow location all the time and access to storage.
In ST
I created a virtual presence sensor. I used this edge driver. (You can also use a Simulated Alexa Switch if your not wanting to play with edge yet).
In Alexa app
If your Alexa app is setup and linked to ST your device should auto discover. If not, run device discovery. (May need to run it more than once)
Then create 2 routines.
If enter Home location turn on ST virtual device
If exit Home location turn off ST virtual device
If you need more help let me know.
Edited to add: you can adjust the size of the geofence for each enter/exit routine as you create them.