No there isn’t. If you restore your device, you erase everything on it. There are ways to clear up storage without erasing the device. You can delete content to make more room. For instance you can delete movies that you have watched to make more space. If they were purchased from iTunes, you can download them again later if you want to do so. You can also offload or delete apps that you use infrequently or don’t use at all.
Take a look at this for more information.
How to check the storage on your iPhone, iPad, and iPod touch - Apple Support
This one might also be helpful. I caution you to make absolutely sure that you know what you are getting into if you choose to use iCloud Photos. If you go that route, do some research first.
Manage your photo and video storage - Apple Support