An esim in current phones expands the possibilities for travel data service quite easily. An Airalo $20 Euro esim gives 5Gb of 4G data for 30 days, and allows tethering. You can configure the service start date at time of purchase so it is in effect wheels down. I have used them on a few continents and they are reliable and save the hunt for a cell store with an honest rep who speaks English and has a sim in stock. The newest iPhone has dual esims, so you can have your main voice line on esim and still add a second esim data line. This will allow for making free WiFi calls to and from the US over the simulated WiFi the IMS service permits.