It depends on the smart switch you're using. I'm not aware of any that work with an existing "dumb" dimmer, but I could just not know of something that exists (seems unlikely, though). As noted above, most require an add-on/companion switch. Some can work for on/off with an existing dumb switch. Lutron mostly avoids this with Caséta by using remotes powered by batteries in multi-way locations (these being Pico remotes, something you could use on Hubitat for any purpose including this with any switch or dimmer if you have Caséta or RA2 integrated in Hubitat).
Something that wasn't mentioned: the new Inovelli switches will let you use another smart dimmer on other locations if you want. I can't imagine why you would (It's probably more expensive and an add-on would also give you dimming, but I guess with Inovelli you'd get to make use of the LED bar at the other locations too). They're the only ones I'm aware of that work like this--they can actually work in any of the above configurations depending on whether you have a neutral or not (again, there may be something else I'm not aware of). You can get the switches now, but you'll have to wait probably a couple weeks for the dimmers to finish mass production.