Can I buy more storage on my iPhone without buying iCloud storage? My phone has 32GB, is there anyway I can upgrade to 64GB?

Yes, buy a new iPhone with larger capacity.

iPhone capacity cannot be increased after purchased.

Just like Bailee, you will need to purchase a phone with more memory capacity if you want to keep more stuff on it.

How do I buy more space for pictures and other stuff

It’s not that easy to just buy a new IPhone for some people

my phone was used out 45G storage,I want buy 250G for $2.99/monthly,how to do this?

Buying iCloud storage won't solve your on phone storage UNLESS your photos are taking most of your space on the phone.

In that case, if you have iCloud, then you can choose to optimise phone storeage, and your photos will be stored full size in iCloud, and only lightweight viewable versions will be stored on the phone (you cannot delete these or they will also be deleted in iCloud)