Sorry, it won't work
You are not making an extract, at least not in the sense in which you are using the word. You seem to expect to use it as a flavoring for other foods, while what you are making is simply a liqueur.
It is not possible to make that kind of concentrated flavoring in home conditions. It doesn't matter what you do - heat, time, or whatever. You neither have much flavor in the cherries to start with, nor do you have any efficient methods to get it out of the cherries, nor can you later concentrate the result.
Why do sources speak of "extraction"
The word "extract" has a much broader meaning in the kitchen than simply "concentrated flavoring agent". When you find sources which suggest that longer time will give you better extraction, they mean that you will get a nicer, rounder-tasting liqueur with more subtle notes. If you try heat, you will get quicker to a cherry-tasting liquid, but it won't have a more intense taste, just a different (and harsher) cherry taste. There is a reason people pay more for longer-stored wines and vinegars, you cannot replace time by anything. Also, even if you start out with more cherries (or with dried cherries as suggested in other answers, which amounts to the same thing, more cherry mass per unit of alcohol), the results will be slightly more intense, but nowhere near the expectation you described.
How can you get cherry flavor instead
When you add liqueur to something like whipped cream, you do get a nice flavor note - but it will always be subtle, not a strong "wow, I am eating cherry cream now" feeling. If you want to get that, you have to use commercial flavoring - or better yet, do the main part with commercial flavoring, and also add a teaspoon of your liqueur, to round it out with more complexity from the actual cherry.
A second option is to purchase freeze-dried cherry powder. It does have drawbacks, such as being very expensive, adding some slight grittiness to your cream, the need to use relatively large amounts (but at least it is dry, so it won't ruin whipped cream or ice cream bases) and not being as flavorful as an actual flavoring. But it is still popular with some bakers, and it does tick the "there are real cherries in it" psychological box. Again, you can combine it with a bit of liqueur for best results.
If you really want a homemade route, the best thing to do is not to extract anything, but to use a dehydrator. You will have to puree or juice the cherries and start with a fruit leather recipe, but interrupt it before it has gone hard. You also have to stir every couple of hours, to prevent a skin from forming. The result will still not be as concentrated as a commercial flavoring, but you can create a variety of desserts if you use enough of it. For example, if you have access to double cream (48%) you can dilute it with the concentrated cherry puree down to 33% and whip that. Or, more doable, whip the cream separately, then fold the puree and a thickener to create a cherry mousse. If you have your own cherry tree, this is a great way to use up a large amount of cherries without producing a lot of dessert.
I will mention briefly another option, because other answers talked so much about heat and volatility. If you feel playful and want to continue using alcohol and heat, your best option is to do a hot distillation. You don't even have to make cherry wine or cherry mash (although you could); redistilling your liqueur should work too. A small scale apparatus won't be too expensive, but you may have difficulty getting it locally if you live in a place with strong anti-moonshine laws. The downside is that the result will be not a flavoring, but a cherry brandy - which will have similar flavoring uses as the liqueur, but with a different flavor profile.