OK, most devices have 3 ways they can store contacts: SIM, device (unsynched), attached to an account (synched - commonly to a Google account but other accounts can also sync contacts). Some have fewer options, e.g. Pixel devices don't offer on-device (unsynched) contact storage, at least not through their default contacts app. I don't have a recent Samsung device so don't know exactly what options you have, so am going to talk in generalities here.
Getting contacts off the SIM card should be easy: in the Contacts app's settings there will be an option to import contacts from the SIM (that's been there on every Android device I've ever met that had a SIM slot). Exactly where in the app's settings this will be will depend on the app (on my phone it's sitting in plain sight under "import", but I've had older phones where I've had to go deeper into the settings to find it - "manage" is also a word to look for, as the option is likely to be under that). That should offer you a choice of what you import them to (device only or synched to some account).
As for the default, again my contacts app's settings have that sitting in plain sight, but I can't guarantee it isn't in some sub-categeory on yours. But there should be an option in the Contacts app's settings somewhere (if not clearly visible it could be under editing options, account options, or contact management. Samsung mess with settings more than anyone else, so there's always some extra fun in guessing what they will have done
![Wink ;) ;)](/styles/smilies/google/wink.png)
).
Since device-only contacts are not synced, if anything happens to the device you will lose them. My suggestion would be, once you have set up your contacts, to go into your Contacts app's settings and "export" them to a vcard (.vcf) file. You can then copy this somewhere safe (off the device), and then if you ever need to you can import it back into any Android device and pretty much any contact management app on any platform (Android, iOS, Windows, Mac, Linux - this is why standards are good and proprietary formats a pain in the proverbial
![Wink ;) ;)](/styles/smilies/google/wink.png)
).