No question is closed as "opinion-based". That's not a close reason used on the SE network.Instead, questions can be closed as primarily opinion-based. That means that opinion is to some degree allowed (but it should be backed up, e. g. by research, but also by personal experience). But it has to fit the SE model: A question with one clear question that, in principle, has one correct answer. Several answers then compete for the top spot, in the best case.
That excludes questions with several distinct answers that can be equally correct (e. g. everyone just posts their opinion).
Another problematic format are polls. I give one example: My family is upset I don't visit them as often as before (Note that it was later edited by another user, not the OP (who also didn't leave comments), so it now looks more suitable for SE but is a different question. But I link to the original version that was closed as primarily opinion-based.)
The post contains 2 questions: "Am I wrong for this?" and "Am I wrong?" It's a poll and such questions are not deemed a good fit for the SE model. They allow for 2 answers, "Yes" and "No", and their score decides whether the OP is wrong or right.
They are unlikely to contain useful advice (because that's not what they are asking for) and are asking for validation. A much better fit are questions that ask How to do something? as they can get useful answers outlining steps to take.
And in case someone might argue that a poll question could be useful by telling them their approach is correct (i. e. "Yes"), such an answer to a How question is also possible. (A "No" answer to a poll question is even more pointless, it needn't tell you how to do it better).
Another kind of primarily opinion-based question are Should I ... ? question, which want us to make decisions for the OP. But we can't do that and no amount of detail they provide would be enough for us. They need to decide for themselves and then ask how to put it into practice. We can't decide whether it's a good idea to actually marry their fiancé or what their boss thinks about them, etc.
In general, it's useful to keep in mind that Parenting.SE follows the same model as a stack like Stack Overflow. Some changes have to be made, but the basic model is the same. And a question like "Is my code awesome?" on Stack Overflow is not a good fit either.