Correct. And also for completeness, to shrink an LXC disk on zfs:
zfs set quota=<new size> <disk dataset>
zfs set refquota=<new size> <disk dataset>
pct rescan
Example:
root@richie:~# grep subvol /etc/pve/lxc/999.conf
rootfs: local-zfs:subvol-999-disk-0,mountoptions=noatime,size=4G...