In general yeah. Like a basic distilled water one has you feed water into it and you get steam out (or use some form of doped water or heavy water or so and get high pressure steam out, not usable as normal steam but holds a lot more heat), or you can put a salt slurry into it and you get molten salt out or a variety of other fluids, some of which may be useful on their own for various purposes.
But once you get the fluid out (and different fluids have different aspects of them, like some may moderate and some may not, etc… they all differ) if you aren’t using it for some other purpose you can send it to a heat exchanger, which takes the ‘hot’ fluid and puts back out the cold fluid, but that then gives you heat on its main face, which you can sit a crucible on if you want for example as a nuclear powered crucible (that will likely melt quickly unless you throttle the reaction well, lol). Or you can put the heat into whatever can take in heat (HU is the GT6 heat units, another of the many many energy units of GT6), like a boiler to make steam out of (like in large quantities). Etc… It’s lot of little pieces that you hook up however you want to accomplish whatever tasks, rather than lots of specialized magic blocks.
The fluid you feed in to the reactor, the types of rods you put in, what’s around it, etc… etc… all changes how it acts and how it puts out neutrons and how they generate heat or whatever. So to make a breeding reactor you set up up in such a way, like to run hot and fast an inefficiently, or you might make a reactor that is larger and cooler and self moderating to generate a lot of power for literally weeks at a time, etc… It’s all in how you build it.