Hi @islands7
If you have a ZTE ZMAX 2 check if it has Android Ver.6.0 installed.
If not update the firmware to this version and then you can ''try'' to [https://www.lifewire.com/set-sd-card-as-default-android-6743109|format the SD card as internal storage].
If you need more storage change the SD card to a max of 64GB to give a total of 80GB which is no more that what was possible before but now you can have apps on the SD card as well.
I did say ''try,'' because a lot depends on what options the device manufacturer will allow with the firmware that they use in the phone.
Also I'm not totally sure with your model that if the above works that when formatting the original SD card it might erase everything from the card so maybe ''do a backup first'' or use a new SD card