The scope being larger than a single world is a pretty common expectation for Space Opera.
To quote TV Tropes:
"Space Opera refers to works set in a spacefaring civilization, usually set in the far future or A Long Time Ago, in a Galaxy Far, Far Away.... Technology is ubiquitous and secondary to the story. Space opera has an epic character to it: the universe is big, there are usually many sprawling civilizations and empires, there are political conflicts and intrigue. The action will range across part of a solar system at a minimum, and more commonly will extend over large tracts of a galaxy or several. It frequently takes place in a Standard Sci Fi Setting. It has a romantic element which distinguishes it from most hard science fiction: big love stories, epic space battles, oversized heroes and villains, awe-inspiring scenery, and insanely gorgeous men and women."
And Wikipedia:
"Space opera is a subgenre of science fiction that emphasizes science fictional space warfare, with use of melodramatic, risk-taking space adventures, relationships, and chivalric romance. Set mainly or entirely in outer space, it features technological and social advancements (or lack thereof) in faster-than-light travel, futuristic weapons, and sophisticated technology, on a backdrop of galactic empires and interstellar wars with fictional aliens, often in fictional galaxies."