You can do this. You need to learn how to do multiple things.
You cannot do it like
1)where the app would receive SMS from an Arduino
Your Arduino is sending that Text message? If so the Arduino ‘knows’ what the coordinates are so the Arduino could just send the coordinates to your app and display it in the Label using BlueTooth. For some reason you want to send an SMS using the Arduino. Yes, your Arduino probably can send a text message. When the text arrives, parse the message and extract the latitude and longitude.
Once you get that far, ask again about
2)and then the app displays the SMS on the label
3)extracts the GPS coordinates
5)displays the coordinates in the map.
Sure, it can display the coordinates once you know them. You can do this several ways. Do you know how to use the MIT Map component?
yes. If you use the Map component, you can change the zoom level of the map by pinching or double-tapping to zoom. You can also use the ShowZoom.true to show zoom controls .
What you can do with the Map control is described in Map
If you save your route to a LineString and save the Points to a TinyDB or CloudDB or FirebaseDB or Googlesheet you can reproduce the route on a map using the Map component.
I do not know. It appears you download a map file using that app. The offline map seems to be a map on an OpenStreetMap tile base, perhaps in kml format. Do you have the kml file? I seem to recall the that it is possible to extract the hiking map trail to a LineString. If that is true, then the following applies and you might be able to post some of the data from that map to the Map component:
Is this possible? What you do depends on why you need the coordinate information in kml format. https://developers.google.com/kml/documentation/kml_tut and why you need to work with Google Earth. KML traks can be displayed (with some transformation) on the Map component as a LineString.