Would it be acceptable to edit the content and title to say "What if a device draws less current than the power supply provides?" if that would make the question more searchable? Would that be considered as changing the author's intent?
You should ask this question on each site where you want to participate. Because each site will have separate standards as to how it handles edits. For example, on Code Review, it is site policy for "question" titles to not be questions.
For Code Review specifically, it makes sense to have titles describe the code to be reviewed rather than the desired results of the review. Otherwise, every title could be simply, "How could my code be better?" Such titles would be useless on Code Review, as they wouldn't really help people choose which posts to read. For people posting on Code Review, that question can be implicit. But on other sites, the reverse is true.
For this reason, this policy is going to be set on each site separately. A sitewide policy on this would be a bad idea. Even on individual sites, the policy might have to be different for different questions. In your example, you talk about current values. Current is highly variable with many possible values. But what if we instead changed this to voltage? Voltage values are often standard. For example, US house voltage is commonly 110 or 120, with 220/240 available. Editing out the 120 or 220 would make the question less searchable or at least less responsive. Because there will often be different solutions depending on that choice.
Anyway, each site is going to be better able to recognize what issues are likely to exist on that particular site. And they can tell you if a general rule will work or if you need something more adaptable on that site.
If there is an answer that provides both
- The generic answer to the generic question you propose
- The exact example given in the question
Only then I think it's an okay edit.
If the generic answer is missing, you just raised the bar for answers. A person writing an answer for the exact example, might not have the time to craft a generic catch-all answer. That means they don't answer and the OP is left hanging for something they didn't do.
If a generic answer without that specific example is there, you removed any incentive to actually help with the OPs question as asked. Again, the OP does not get what they want, even though they did everything right.
So, to summarize, if the user is happy because they got an exact answer to the exact question they asked and the answer is already more generic than just this question, only then it is okay to broaden the question, leaving in the exact example given.
Otherwise, feel free to ask your own question, not changing other's.