Can an authorized user activate e/SIM?

I was browsing T-Mobile online to find a way to get a new SIM on my new phone. My old phone is very old and uses the old, larger, SIM format. None of the options are allowing me to keep the same phone number and getting a new number means adding an unnecessary line. "Already a T-Mobile customer, number can't be transferred to T-Mobile. We'll provide a new phone number after your purchase complete."

I looked around further to and found an option to "Update device SIM" on my account dashboard which led me to the contact us page and having to call customer service due to security reasons. So, I called CS and tried to get this SIM thing going, but I could not because I'm not the Primary Account Holder. However, I am an Authorized User but that didn't cross my mind while I was speaking with CS.

As I had also found this page: Usa la tarjeta SIM más nueva para tener una excelente experiencia en la red | Asistencia de T-Mobile
That says,

• Si ya no tienes la tarjeta SIM que vino con tu dispositivo 5G, contáctanos o visita una tienda para recibir una tarjeta SIM de reemplazo.
  Por tu seguridad, la solicitud debe hacerla el titular de la cuenta o un usuario autorizado.

But this page is in a different context, so I guess it doesn’t apply at all.

Anyway, I guess my question is basically, can an authorized user get a SIM or activate an eSIM through a call? I would guess not as I don't think it'd be something CS would overlook.

I thought it would be easy to do but I guess I’ll have to stop by a store after all and pay whatever fee there is for going in person.