Need your explanation

In addition to what Ijustwanttolookattheforums stated above you have a look at the following to assist with freeing up some space on your device - About storage on your device and in iCloud - Apple Support.

"Free up space on your device

You can make storage space available on your iPhone, iPad, or iPod touch when you use iCloud Photos and turn on Optimize Storage. Or you can remove content from your apps—like photos, music, and Podcasts—or delete the apps that you're not using."

You are paying for iCloud storage. iCloud storage is seperate to the storage on your phone. You can not buy or add extra storage on your phone so the storage on your phone is and always will be 32GB.

If you're trying to save space you might want to look at the suggested reccomendation and review large attachments which are taking up a lot of space on your device.

Also you could try Changing Messages Settings so your messages delete sooner, by default it is set to keeping forever.