This is up to you and what options you have available. If you have a computer or storage device then I would recommend making a backup on these devices. there's also a lot of options available for online backups, the one recommend by Samsung is onedrive. I'm currently using my computer backup and google one for my online backup.
I installed OneDrive at Samsung's suggestion, since they keep saying your gallery won't sync and backup to Google photos after a certain date. I spoke to someone at Samsung support, and this isn't true! It's just that Google photos are no longer offering free unlimited storage space, and you only get 15GB free now. If you are, or do, run out of storage, that's when it stops syncing. I just bought 100GB of storage for $1.99 a month! The problem with OneDrive is it only syncs photos from your internal storage! I have an SD card, and keep all of my gallery photos in folders stored on the SD card so I don't take up my internal storage. When I take a picture, it syncs and stores in OneDrive, but as soon as I move it to a folder on the SD card, it removes it from OneDrive! And if I delete a pic from my gallery, it also deletes from OneDrive! What's the sense in backing it up to there if I can't remove it from my gallery? Google photos doesn't do that! I can delete from my gallery and it's still stored in Google photos. I have pics stored in there from many old phones, all the way back to 2014!
