How to get a free storage.i cant buy it

SAee this Apple article:

If you need more storage, have a look here:

https://support.apple.com/en-us/HT201318

Just to be clear: the storage being discussed here is online storage at iCloud, accessible to any device signed into it for syncing data (copying it so that it appears on other devices) and for email etc.

It is not actually on your phone: the storage on an iPhone cannot be increased.

TANSTAAFL