There are unlock from carriers, unlock to install cracked apps (always a bad idea) and unlocking to delete factory apps.
If that site does not answer your questions they are unreliable.
Here I have yet to need any of the unlock reasons in years.
I want to Carrier unlock my Samsung Galaxy S9+. The phone is AT&T. I found a website unlockplus.com .
They told me that is possible.
What do you think.
The unlocking websites are reliable?

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic