What if anakin had stayed in the dark side in the clone wars
If Anakin had stayed in the dark side during the Clone Wars, he would have continued to serve as Darth Sidious' apprentice, carrying out his orders to orchestrate the fall of the Jedi Order and the rise of the Galactic Empire.
With Anakin's strength in the Force and his military prowess, the Clone Wars would likely have ended swiftly and in favor of the Separatists, allowing Sidious to take control of the galaxy unopposed.
Without Anakin's redemption in Return of the Jedi, the galaxy would have remained under the cruel and oppressive rule of the Sith for the foreseeable future. The Jedi Order would be all but extinct, and any remaining Force-sensitive individuals would have to go into hiding to avoid detection and persecution.
Overall, if Anakin had stayed on the dark side, the Star Wars universe would have been a much darker and bleaker place.