Does T-Mobile really support RCS?

tidbits -

Thanks for the details.  I tried it, and . . .

First I had to learn about eSIMs.  This is my first phone with one, and I had been wondering why each of my communications apps was showing options for SIM 1 and eSIM 1.  After researching it, I realized the store had not transferred the (very recently updated) SIM card from my old phone, yet some apps on the new one (or at least their Settings screens) were acting as if one were there.  I went ahead and transferred the card, then went into the SIM Management and turned off the eSIM. 

I then followed your directions above.  I found that the default Samsung Messages app would not show me an option to turn on RCS, so I went back to the Google one, and it does.  But when I "Turn on RCS chats," the Status was shown as "Setting up..." "Trying to verify your phone number," ans it just hung there interminably.  . . .

That is, *until I reactivated the eSIM and set it as Primary.*  Now RCS shows Status: Connected.  And I can send messages properly, with RCS as default and "covert to SMS  - only using the eSIM.  Interesting.  So I guess I will reserve the SIM card option for overseas use, if needed. 

Nuevamente, gracias.