Of course the new iPhone 11 just came out, but you can still get previous models as well.
Apple has a handy comparison chart here:
Tip: You can use the link at the top for “See all models” to get a quick overview of newer and older models. From the main compare page, you can also choose which models to compare by selecting them from the drop-down.
You might also want to go into an Apple store and get hands on with a few options to see what feels best for you. There are people at the store who can answer any questions you might have when comparing whats available.
Once you have your new phone, don’t forget Kim’s ebooks! There is one called “iPhone for Seniors” with a walk-through on setting up your new device (It’s not just for seniors, it’s for everyone from first time iPhone owners to geniuses!). You can find the ebooks in the menu to the left or at the link below:
Hope that helps!