Yes. That is what I was saying about using driver.
By default, what is written in Drivers panel is just the variable var+1.0.
You can write 1/var , instead. Then, you just have to precise other object scale as variable.
You can set driver for one axis. Then, copy/paste driver for other axis and just adapt variable to use relevant axis.
https://docs.blender.org/manual/en/latest/animation/drivers/drivers_panel.html