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You want to set the CC to the desired level. The voltage will vary, as pointed out by Barkuti.
Leds are voltage dependent on output but they have to have a source capable of flowing enough current to meet that voltage.
Look at this xhp50.2 test provided by djozz.

If you want to run a led at a certain current you must supply a associated voltage to reach that current along with enough overhead voltage to account for losses.
As barkuti pointed out you have voltage losses and differences in vf’s that can vary.
By adjusting the CC (constant current) to a set value it should insure the led will never see more current than what was set. No matter what variances happen in losses or vf’s.
When led’s and wires along with electronic components heat up their values change slightly.
Let everything run for a little while then set CC to the value you feel safe with.