I have done everything and I can't get the icons to appear in MI 10T and my phone company (Claro, Dominican Republic) is compatible with these functions.It is working with Dual Sim.
See atchm. Dual Sim, LTE Data andVoLTE.
Using * # * # 4636 # * # * I see that they are disabled and grayed out, But in the phone configuration, if it is activated