i need more storage

Try to free up iPhone device storage see this Apple articles below:

If you need more space for an update on your iPhone, iPad, or iPod touch

If you need more space for an update on your iPhone, iPad, or iPod touch - Apple Support

How to check the storage on your iPhone, iPad and iPod touch

How to check the storage on your iPhone, iPad and iPod touch – Apple Support (UK)

Clear Other storage on your iPhone or iPad

Clear Other storage on your iPhone or iPad - Apple Support

-> What's the difference between device storage and iCloud storage?

What's the difference between device storage and iCloud storage? - Apple Support

It is not possible to expand the internal memory of the iPhone. What you can do is buy space in iCloud. If you have many photos, you can choose to optimize the size of them locally on your iPhone, and leave them in original quality stored in iCloud.

First, I would recommend clarifying what takes up space on your iPhone, and possibly. get rid of what you do not use. You can get an overview of what your internal space is used for here: Settings -> General -> iPhone Storage.

You can now decide if you want to buy space in iCloud. It's important to know that iCloud does not expand your internal memory on your iPhone, but gives you space in the cloud so you can store some things there, and other things internally, thus saving space. If you have VERY large apps or files on your iPhone that are to blame for running out of space, then you will have to consider deleting them, or moving them.

You can read more about iCloud Storage here:

iCloud+ plans and pricing - Apple Support

Here you can read how to buy extra iCloud Storage:

Manage your iCloud storage - Apple Support

You can read here how to store Photos in iCloud:

Use iCloud Photos to store photos in iCloud - Apple Support