How do I move storage from one phone to another one ?? Both iPhones

You can’t move storage from one device to another. If you are asking about iCloud storage, that is tied to your Apple ID, so you need to do nothing to use that storage on another device. When you sign in to your Apple ID on the new device, the iCloud storage is available to you.

If you want to set up a device so that your apps, data and so on will transfer to the other device, you can restore from a backup, or use quick start.

Transfer data from your previous iOS or iPadOS device to your new iPhone, iPad, or iPod touch - Apple Support

You are copyin the apps, data and purchases from one device to the other one. The phone from which you are transferring will remain intact. All of your stuff will still be on the old phone.

Yoy do not need to take your phones to an Apple Store for this. It really is quite easy to do. Read this kb article. It explains exactly what you have to do. Make sure that you backup the old phone first.

Transfer data from your previous iOS or iPadOS device to your new iPhone, iPad, or iPod touch - Apple Support

This explains how to backup your phone.

How to back up your iPhone, iPad, and iPod touch - Apple Support