Far from unlimited. Almost all fusion power plant concepts are thermal power plants. These directly contribute to global warming, and you can’t scale up by more than a couple of orders of magnitude without causing significant climate change.
In the end you’d need to use panels to radiate the waste heat directly to space, but then you have similar land use limitations as solar panels.
There’s no reason to think we actually need that energy. Advanced deep geothermal is probably much easier than fusion. With that you’ve got geothermal near the poles, solar everywhere else and wind/hydro/wave/tide to supplement based on needs and availability.
Helion fusion power plant concept is not thermal. So we can probably make a lot more electricity without heating up the planet too much. In the end it too will be limited by the heat added to the planet.