Do you mean a triple gang switch box? Three regular size switches side-by-side with one plate that covers all of them, like this:
If that’s the case, no problem, most zwave switches can be put into a triple gang box, although read the instructions for any specific model that you were interested in. Most commonly there are tabs on the side of the switch that you have to break off in order to get it to fit. Note that if you do have to remove these tabs then the total current load supported by the shared circuit does go down, because the tabs act as a heat sink for the switches. But if you’re going to be using dumb LEDs with the switches, you’re not likely to be anywhere near the max load anyway. But do read the specs.
If you mean you have three toggles in a single gang box, like this:
Then there aren’t any standard off-the-shelf zwave products that do that. It’s not impossible if you use multiple in wall micros, but it’s just trickier and you usually end up with a switch design like this:
And you have to do some physical modification of the switch to get it to work.