If your carrier has a backup cloud, that might be the easiest way to go. Many carriers will allow you to use the Samsung Cloud; (Method 3 in link below). I believe the free amount of space is only about 16 gb. That may or may not be enough space for you. You can always buy more. I believe they are teaming up with the Google Cloud in some fashion.
You can also use Google Cloud to backup data (method 1 in link below); But I'm not sure if they backup text messages which seems to be your main concern.
I have Verizon and get a Verizon Cloud included in my plan...600 gb or so of space. Verizon doesn't let their customers use the Samsung Cloud as weird as that sounds!
If your carrier doesn't have that cloud usage, you can use the Samsung Smart Switch which is on your phone already... you would merely need to add the free program to a backup computer (pc or mac) and then you can pretty much back-up your messages or whatever. (Method #2 in link below).
As I said, a cloud backup will be much easier for you to use. I hope this helps some. Good luck!
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Archive and backup are two different things. Ideally, all messages should be backed up automatically and may never be accessed again, except in cases of needing to restore after data loss or device/carrier switch.
Archiving is a way to move individual chat sessions out of your main message feed, but still have them available in a folder to view as needed. For a good example, see Android (Google) Messages. Google also uses it as a place to move suspected junk messages, some of which could be phishing attacks and quite harmful to click on. Obviously, backups are not a relevant solution for such scenarios.