Depends, if you use a lot of storage or not. I’d say go for the double of how much storage, you are currently using on your XS. But storage is severely overpriced on iPhones, so it is hard to say. If you truly need 1TB, I would go for the 13 Pro. I struggle to fill out 128 GB, but maybe that is just me.
No worries! Could be you would have to manage storage a bit, if you go with 256 GB. Question is, if the savings are worth the time you use on storage management. only you can answer that.
The biggest differences are the Dynamic island and a 48 MP camera sensor. Maybe check out some camera comparisons between the models. I think they are notable upgrades, but not something I would pay a fortune for.