Yes, free play or float is adjusted at the slave by changing the length of the rod. The rod is threaded and may even have a couple of flats on it for gripping with a wrench. If you see no threads on yours it may have been adjusted to it maximum shortness.
I always have a hard time judging from photos which style of slave I am looking at but possibly yours is the ‘self-adjusting’ variety - though as David notes even if self-adjusting it must be initially adjusted correctly.
So far as I know, an external spring can be fitted to either type of slave in which case a 1/16" float is used. That measurement is less important than the fact that you need some float there to let the carbon throw-out bearing to back away from the clutch. 1/16" gives that float and enough extra that you are okay until the next time you check it.
Here’s mine with said spring & anchor:
I can feel that 1/16" by simply pushing the clutch operating arm forward.
With a small flashlight you should be able to observe the carbon throw-out bearing and note the desired gap by looking through the rearward bell housing hole:
I tend to be a bit fussy about checking mine and recording the result (note the painted witness mark) as my first & only ‘engine out’ was thanks to a PO who didn’t pay attention to such things.
If you find the push rod is not a suitable length a replacement can be made from a ordinary bolt of suitable length and correct threads.