This phone features 16 or 32 GB of internal storage. Additionally, to increase the storage support, simply buy a microSD card and insert it in the slot. The phone supports a maximum of 128 GB storage support through the microSD cards.
If you want to use apps like Link2SD or APP2SD, the phone needs to be rooted. To root it, access the XDA Forums to learn how to do it. However, the phone has some certificates and if you lose them, some functionality of the phone won't be available anymore.