Background
A recent question asked about designing the biological sexes of alien creatures. Not surprising in our world today, the OP's original question used the word "gender," even going so far as to identify the creatures as "woke" in the original title. I'm not complaining about that — it's the confusion that's the issue. The author thought the creatures had been designed with a third and/or fourth "something" that was called gender, but when you get down to brass tacks, the question was actually about sex and the design was basically the same two-sex procreative system we commonly see on Earth.
I've noticed that it's becoming more common in our world's current sociopolitical environment for the concepts of gender (the biology of relationships) and sex (the biology of reproduction) to become confused.1 That's also not the point of this post — but what started out as an effort to help worldbuilders sort that out... is.
I was going to post a question seeking to help worldbuilders understand what it means to have a "third sex"2 with the goal of Stack participants describing fictional examples. E.G.,
What are examples of fictional three-sex reproductive relationships that worldbuilders can use to guide them when designing creature reproductive relationships?
This would help worldbuilders not familiar with the terminology differences between the biology of reproduction and the biology of relationships. The question would have had the worldbuilding-resources tag, the xenobiology tag, and the sex tag.
Then I realized that our current rules won't allow for a question seeking comprehensive advice of this nature. It would violate the Brainstorming admonition as well as being open-ended (but not, I suspect, in the way Stack Exchange intended) and all answers having equal value.
Question: How can we provide worldbuilding-resources insight? Or have we finally created a version of the rules that killed that tag?
Additional Insight
Assuming one interpretation of Stack Exchange's intent (to be a collaborative resource for solving problems), do we believe one of our goals is to help instruct new worldbuilders in the process of worldbuilding? (Not necessarily confusing this with the worldbuilding-process tag, but that could be involved.)
Our rules make it difficult to produce a "canonical answer" because we require what I'll call "effort-specific questions" (what help do you need with your own worldbuilding effort?) and a canonical answer would benefit from a more general question (Let's say someone might be interested in the following, what guidance can we offer?).
1 And just to add to the confusion, the OP used the word "woke," which has no relevance to either the biology of reproduction or the biology of relationships. It's a word that only has meaning in culture, politics, philosophy, etc. It's not that we aren't completely willing to help worldbuilders to incorporate the idea of "wokeness" into their efforts, only that now we've muddied the question with three types of terminology: reproduction, relationships, and culture. It's amazing how well humanity can muddy the proverbial waters.
2 If you're not familiar with the biological terminology, "sex" specifically refers procreation. Remembering that we're simplifying all this (a political debate is not useful for worldbuilding... well, not in this context). Thus, humans have two "sexes," male and female, both equal and necessary to procreate. Simplistically, a "third sex" might be a creature C that receives the egg from creature A and the sperm from creature B for gestation. Creature C being equal and necessary to procreate.