The short answer is "yes"
A great many questions asked here, even when purely within a worldbuilding context, would probably receive more authoritative answers more quickly if asked on other, more appropriate Stacks.
The long answer is "if you want"
There is a substantial, natural overlap between worlbuilding and the sciences. At a rough guess, 80%+ of the questions asked here could be asked elsewhere with better results.
That's the problem we've generally had over time: Sure, the Earth Sciences stack can answer questions about geology, oceanography and meteorology. But the moment you mention it's for a fictional planet (or the moment they figure out it's not a question about Earth as it is today), you have a high probability of closure. The other Stacks are fundamentally biased (and rightly so) on here, today not there, tomorrow.
Thus, the "real-world questions" decision was made
Almost a year ago (time flies when you're having fun), the mods introduced a proposal to finalize the "are real-world questions on-topic debate." The simple answer is yes, they're on-topic.
Therefore, the basic rule is this:
If you can word your question to meet the expectations of a Stack more dedicated to that field of expertise, you might2 get a better answer more quickly using that Stack. Nevertheless, you're always welcome here, never forgetting that we have expectations, too.
1 I once posted on Electronics.SE a question about whether or not you could self-charge the sound effects used for a potato gun by running zinc and copper rails down the barrel. It took forever to be answered, by one person in comments, because it was perceived as a silly (read: not serious) question.
2 We've experienced the condition where a perfectly sensible question was asked on the more appropriate Stack and didn't receive an answer within a time the OP felt was reasonable, so the question was brought here — which is an example of the simple truth that nothing's perfect.