So, I ”had” the same issues as many on here...I am on the correct data plan but no 5g options under carrier settings, just 4g and LTE.
I called 611, asked to have my IMEI updated, and my issue was resolved. The tech on the phone did say that he could see that there was an IMEI issue and that he needed the number off my phone to fix it.
On a side note I do use dual SIM and was aware that I could not get 5g if using both. The somewhat good news is that if you go into carrier settings and disable one line you can get 5g on the still active line. I had heard that you would need to manually remove the physical SIM in order to get 5g on the e-SIM but that is not true. At least not for me.