You could probably make this case for Star Trek: The Next Generation, Deep Space Nine, and Enterprise as well. TNG and Voyager probably fall closer into the "highly-episodic" category, while DS9 and Enterprise tend to be structured around larger ongoing plot lines. I think they all have the same kind of merit as Voyager with regards to discussions about issues and moral decisions.
Depending on the 11-year-old, you might be able to make a case for Seth Macfarlane's The Orville, which can be a bit more hit-and-miss, but does have some truly excellent episodes, particularly in Season 3.
The newer Star Trek series coming out are probably too gritty if the parent is worried about age-appropriateness (I believe Picard has a TV-MA rating?) and unless you really like The Original Series, it's pretty noticeably a product of its age and I personally had trouble staying engaged by it when I was that age.
I actually find it very interesting as an adult. It's obviously aimed at kids but the story is not bad considering other current star trek series (discovery in particular)
Depending on the 11-year-old, you might be able to make a case for Seth Macfarlane's The Orville, which can be a bit more hit-and-miss, but does have some truly excellent episodes, particularly in Season 3.
The newer Star Trek series coming out are probably too gritty if the parent is worried about age-appropriateness (I believe Picard has a TV-MA rating?) and unless you really like The Original Series, it's pretty noticeably a product of its age and I personally had trouble staying engaged by it when I was that age.