Yes. The reason more humans can live on the planet than the planet could "naturally" sustain, is that they employ outside energy to produce food, shelter, and raw materials.
So more energy, we can support more humans, or existing humans with a higher standard of living.
Three things that you might worry about "go away" with practical fusion energy:
1) Hunger
2) Anthropogenic Global Warming
3) Fresh water supplies
They go away because high energy farming techniques become much more cost effective, fusion power contributes no CO2 and can actually extract CO2 from the atomosphere for commerial use, and the water in the oceans can be desalinated on demand.
It also eliminates many things that cause human suffering, coal mining, oil drilling, fuel transport (oil and coal and gas), smog (electric cars are more cost effective, no more coal fired power plants), and warmth/cooling (if your electricity is cheap enough, everyone can have air conditioning or heat to counteract outside temperatures).
So yes, a practical fusion system will change every aspect of the world.
To clarify: maybe in a more rational, informed society, where we could actually keep building and rebuilding newer generations of fission reactors, then maybe it wouldn't matter as much. We'd have safe reactors and a very small amount of waste products, at a lower residual radiation level.
We don't have any of these things though. In this scenario, then it matters a whole lot. Fusion (I refuse to use the word 'nuclear' here) reactors do not meltdown(nor do the newest fission designs). They generate very little radiation, if any. They have no waste products.
Basically, they remove the "NOT IN MY BACKYARD" variable from the equation. And weaponizing concerns for some countries. And, if they ever work, should generate outstanding amounts of power for their size. Using small amounts of fuel that we don't expect to run out at any non-geologic time scale.
It's easier to sell to the public. "look, it's clean, it's natural, it's just a tiny sun".
So yeah, big deal.