My phone’s older than the OP’s. It’s a samsung galaxy A6 (2018).
(Maybe I was just lucky !)
He’s got two cases that are supposed to fit. My suggestion is that he go to the phone case mart and ask someone to help him, not that he try to buy a third.
And that was what? Usually it’s not the same as the official name. For example, my OnePlus 12 is a CPH2583.
On both my phone (Pixel) & my work phone (iphone) the model name is in plain English, what we would expect it to be called.
Interesting–pretty sure no phone I’ve owned has (happened to, apparently) be one like that! So I guess my original post should say “Sometimes” instead of “Usually” 
There’s a model name, and a model number, and they can both refer to what model of phone it is, just in a different format.
When I go into the settings of my personal iPhone, in the “About” section, it says…
Model Name
iPhone 16 Pro Max
Model Number
MYW43LL/A
The silicone cases do have a little stretch to them to provide a snug fit especially when new. You usually have to put a couple adjacent corners in first then end up pushing the last corners and the case together with some force.
They do, otherwise they’d fall off your phone.