Switching to 3g network on Ios26 and later.

Greetings to all fellows!
In my basement, the reach of 4G signals is almost non-existent and I spent my most of the day here. consequently, my phone (SE 3rd Gen) drops a lot of battery to catch them + I always gather complaints from my family and friends, why your mobile always going offline whenever we try? Even sometimes I have to step outside to get OTP's. And most of the times I miss the important transactional messages from banks. I mean a lot of problems.
So, I want to switch my network to 3G. But it doesn't showing up in network selection settings in cellular section.
Only 4G, 5G Auto and 5G showing up here.
I did a bit of research to find 3G, But came to know that apple has no saying in the matter, only cellular network decides what to show here. But I don't see this claim worthy, because in the same place when I insert the same sim card on my older Iphone 8, 3G section showing up there. but not on this 3rd gen. On more older SE 1st gen, even 2g showing up, same place, same network, and the same sim card.
So, any suggestions from you guys how I can switch to 3G network?
In ideal case, 2G which my carrier still supports, is the best option.
Or it would be great if we can do it with some shortcut, like if my phone connects to a specific wifi, switch the network to 3G or/ 2G.
Of course, appreciations in advance..... 😊