It depends on if you're running it as a partition or not.
If you're using it as a partition, then only a partition tool would be able to resize it, and that's most likely not a good idea on a running server; it could crash your file system to the point where you'd have to do a bare metal restore.
If it's not a partition, but a simple subdirectory it gets sized as required.
If it is a partition and you need to resize it best you ignore it, and create a virtual partition to mount at the same mountpoint.