…this may be of use to you:

It’s init=/usr/lib/raspi-config/init_resize.sh in /boot/cmdline.txt that expands the partition size before /etc/init.d/resize2fs_once runs. If init=/usr/lib/raspi-config/init_resize.sh is removed, /etc/init.d/resize2fs_once still runs /usr/sbin/resize2fs which finds there’s nothing to do and immediately exits without anything being changed. /etc/init.d/resize2fs then removes itself and it’s end-of-story.

https://forums.raspberrypi.com/viewtopic.php?t=313003