What can I do with the Set Radio Band Mode option under test menu?

[Suman72]

If we dial *#*#4636#*#*, tap on the phone information and then tap on the three "..." at the top right corner of the screen we can see the  Select Radio Band" as the first option. If we tap on that we can see six options under the  "Set Radio Band".

1. Automatic

2.Europe

3. United States

4. Japan

5. Australia

6.Australia 2

What will happen if I tap any of this option? Will it add any specific band for that region which is not originally available in the model? After selecting any of these option how can I go back original factory settings? Will the Reset Network Setting option under the System>Reset revert the changes? 

I have purchased the Xperia Xa2 at USA but it does not support the LTE band 3 and 40, used by the carriers of my home country. Can I use this option to enable band 3 and 40?

[Qatrium]

@Suman72

I saw multiple reports of people unable to do any calls or use their data after they played with these settings, so proceed at your own risk.

[Suman72]

I know. That is why I want to understand the function of each of these option before playing with this menu. Do you have any details?