I should first mention that I also meant "Is it OK to...?" and phrases with more or less similar meaning by mentioning the phrase "Is it possible to...?" in the title of this question.
Although this could be an opinion-based question, and the best choice for each title may differ and depend on each question, case by case, I really have a serious problem choosing the better one, and I happened to have a bad experience of negative reaction for each of those cases.
This is my opinion, and you can skip this part.
In my opinion (and maybe yours), as time goes by, asking a question which does not have a potential for downvotes and negative reactions becomes harder and harder.
There are many trivial questions without enough or even maybe without any search efforts with lots of positive feedback / votes. But the difference is, they have been asked a decade ago or close to that time. As if there was some type of golden age in the Stack Exchange network history when you could freely, and without any fear, ask any type of question you have.
But now, if you don't spend lots of time researching your questions using different sources including Google and the Stack Exchange network, your chances for getting negative feedback is very high. Or at least your question may end up with "possible duplicate of ..." comments, even if the question is different but happens to have some similarities.
So I think, now, it is also necessary to study or at least consider the psychological accepts of questions and their titles too!
Compared to "How to...?" style, "Is it possible to...?" questions seem to be safer and have lower risk of negative feedback, although I had advices on my "Is it possible to...?" questions, telling me to use "How to...?" style. And I had negative feedback on my "How to...?" questions as well.
To clear the situation more:
I personally prefer to use the "How to...?" style. It is clearer that you are asking for a method of accomplishing something. But many people (usually with high reputation and possibly with low patience) interpret the question as if the original poster believes / assumes / suggests that "It is possible to...", and now asks "How do I do it?". And, if the thing they are asking about is possible (and / or considered to be a good practice), it is OK. But if it is not possible (and / or not considered to be a good practice), the question will most likely receive negative feedback (maybe rightfully so).
Just take a look at the first comment of the question that I asked recently How to cast pointers to arrays in C++. Although I clearly mentioned that I am not sure if it is possible to do the thing by mentioning "So is it OK to cast pointers to arrays in C++?" in the question itself (not the title), the first comment was "... correct way is not to cast at all. Why do you need that?". I also got a downvote for that question.
This might be a personal experience for me, but I also have seen such negative reactions happen to others' questions as well.