I got my iPhone 12 Pro from Apple a few weeks back, plugged in my SIM, and got the message to instal a 5G SIM card. A Verizon Store swapped the SIM card to a 5G card at no cost, but I did not upgrade to 5G service. My loyalty plan is $40 less expensive each month, and there is no 5G near me. My phone works fine. My guess is that once 5G rolls out here, there no longer will be an up charge.
There are 5G Nationwide network and 5G Ultra Wideband network plans. None of our personal or the many business phones have any uncharge or plan changes for 5G Nationwide.
After just spending nearly an hour with Verizon upper tier support the woman confirmed that again.
My latest fix from Verizon frustrated me in that I had to do a network setting reset but after pushing a setting and watching my phone do AAA she said my problem should be fixed.
The woman warned me there is a lot of construction and upgrade going on near my home and main work site and until that's done I might still notice issues from it. When I've been in a few spots and the general area 85 mi away the 5G Nationwide has been fantastic.
If your phone is up to date be aware of your 12 cellular settings. There's the 5G on, 5G Auto, and LTE. Also Allow More Data on 5G, Standard and Low Data Mode. It could be some who are complaining about a lack of performance with a test app or site have that because of settings choices.