how do you transfer data to icloud rather than saving it to phone storage?

iCloud is more of a syncing service, if you need to free up spacecon your phone, you will need to delete stuff.

Here are some helpful articles that can guide you on how to free up storage space on your phone.

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

Manage your photo and video storage

Manage your photo and video storage - Apple Support Manage your photo and video storage - Apple Support

Clear Other storage on your iPhone or iPad

Clear Other storage on your iPhone or iPad - Apple Support Clear Other storage on your iPhone or iPad - Apple Support

What data?