I'm not sure if this applies to the Fold 2 but this article says you no longer can add on Care+ after purchase for the Note series... so you may want to find out if that's the case for the Fold 2 or not.
Samsung's Care+ protection plan can't be added to the Galaxy Note20 post-purchase
It seems like a permanent change this timewww.androidpolice.com
With regards to carrier insurance, I've heard nothing but horror stories on carrier insurance replacement phones (typically through Assurion). Plus the cost is high... high monthly premium plus a very large deductible. Better off just putting some of that money into a savings account in the off chance something happens to your device.
Don't forget many credit/debit cards have their own insurance as well.