Is the iPhone's eSim for the home or roaming carrier? The XR, XS iPhones feature eSIM capability. Assume that the user lives in the US and uses T-mobile.  Does it make sense to use the eSIM with the home carrier or to use it with roaming carriers the Caribbean and EU countries?

If I assign the eSIM to T-mobile (USA), can I expect the phone to roam exactly as if it had a conventional SIM card?
The eSim can be used both for home and roaming as indicated by Apple's Website:


  Here are a few of the many ways you can use Dual SIM:
  
  
  Use one number for business and another number for personal calls.
  Add a local data plan when you travel outside of the country or region.
  Have separate voice and data plans.