How does setting up a iphone phone plan work? (Payment vs gb storage?)?

I'm planning on getting a iphone xr in October… But I was looking at the iphone phone plans and they seem to vary and are kind of confusing since this will be the first phone I ever by myself. Anyway… If you get the 64gb iphone. But you get a phone plan that only has 30gb on it, do you still get to use the other gb's up on your phone for storing pictures etc? Or does taking pictures not count in the phone plan? I don't really want to spend $400 a month on a 60gb phone plan yet. Because if I get the 30gb phone plan (with verizon), it would only be $185 dollars a month which seems way better to me. Should I go with this plan for a year first? Are iphone phone plans really this expensive?

P.S. How would paying for a 30gb amount phone plan work anyway with a 64gb storage on a phone? Does anybody have this type of plan with their iphone w/ Verizon? Any advice for this would be really helpful. Would a Sprint plan be better? Thanks & sorry for so many questions. It's my first time buying my own cellphone…

Added (1). (Buy Myself) Sorry TYPO!

Let's back up a bit. The 64 GB you're talking about is the amount of storage your phone has. This has absolutely nothing to do with the monthly data plan that I'll get to in a bit. With the built-in storage, you can store pictures, apps, movies, videos, music, etc. Just be advised that with iPhones, you can't add more storage. If you want more local storage, you have to buy a more expensive iPhone with more storage.

The 30 GB you're talking about is the amount of mobile data you can use. When you're not on Wi-Fi, your phone uses its mobile data connection to access the Internet. Anything that uses Internet will use your mobile data (when you're not on Wi-Fi). This is the most expensive part (other than the phone), so you will need to decide if you need that much data.

Most carriers advertise their phones on a financing agreement. So they spread the cost of the phone over 24 months (sometimes more or less depending on what you choose) + whatever your plan costs + random fees+ taxes. So you might end up paying $100+/month for 24 months.

Your phone plan has nothing to do with the storage on your iPhone.