I was able to use a 64gb SD card on my old phone that supported up to 32gb. I did this by wiping the SD card into the format fat32 with special PC programs. Custom ROMs do not allow you to change to maximum size supported but with root access there may be another way.
Welcome to Android Central! The limit that is listed in the specs is usually a recommended limit. Bigger cards can usually be successfully used, although there might be a higher error rate. The official specification is probably there to limit liability.