Is it possible to use iCloud storage like an actual storage of my 64gb phone storage?

iCloud storage does not add storage onto your device. It adds storage into Apple's cloud storage system, here you can save backups and photos. There is no way to convert this to device storage.

To view and manage your iCloud storage go here

For example, you could use this to save storage on your phone, by keeping low quality/resolution photos on your phone but keep the high-quality originals in iCloud.

Take a look at this help article for more info Set up and use iCloud Photos – Apple Support