Geofencing accuracy or better presence sensing using phone

I use my iPhone for presence sensing. Living in a small city of 28000 peopleI may have to travel quite a distance, sometimes 5-10 miles, before SmartThings changes my stud to away. Arrival home seems to be a bit closer, but often shows me home before I can see my home. I have the wifi turned on and the phone logs in to my home wifi when I’m home, but often changes status to home well outside the wifi range.
Is there any way to tighten up the distance and accuracy of presence sensing using this method ? As it is, I wouldn’t consider using ST for door control.

Out of curiosity do you keep your wifi on. I found without it one, even thought it is not directly connected I can be over 5 miles from home and it will trigger I am arriving or leaving. When it is on it seems to worked within my designated geofence.

I keep my wifi on. Is there a way to set a “designated geofence”?

In the phone app if you select the menu option on the right part of the screen with the three dots, you will see my Locations in the list. If you select that and then select the gear on the upper right corner you will see options screen for the location selected. One of those items is the geofence map. You can follow the directions to modify the size the field.