How to manually change carrier settings on iPhone?

Question

iPhone

Can I somehow pick up the configs that come for the telecom operator? The task is to force Megafon Northwest to keep forced LTE to the last. I don’t know what the trouble is, MTS normally keeps to the last. And Megafon jumps even with a confident connection. Yes, you can just port the number. But the megaphone suits me more than. I remember during the certification of LTE by Apple, people somehow changed the settings and turned on LTE before the company did.

Answer 1

The same problem is no LTE at all on the Orange Polish operator, and before the update "Apple released iOS 13.3 beta 3 for everyone" everything worked perfectly, the provider itself freezes and does not give an answer and there is no way to roll back.