Darth Sidious from ROTJ & ROS

Just a general question was Sidious more powerful in Rise Of Skywalker compared to: The Return Of The Jeti or the same power wise etc?

He had the power of all Sith... of course he was more powerful. He was the most powerful Sith ever.

Unless you mean before that scene... then we can't really say; he was crippled, but he still seemed... capable, to an extent.