From a purely ZFS perspective, if you had this pool in a mirror/raidz or better configuration, replacing each vdev with a larger, would allow access to a larger zpool (e.g. I used to have a 6x2 TB RAIDZ2 pool, and progressively replaced each 2TB disk with a 4TB disk, allowing ZFS to resilver each time)
However, if this is a single vdev pool, ZFS currently has no way to expand that pool size, other than to do a backup (zfs snapshot+send) and restore into a new pool.