Stack Exchange has, in a roundabout way, answered this question
There are two ways of looking at your post. First, the idea of crediting Stack Exchange, Worldbuilding.SE, or one or more users on Worldbuilding.SE, for their assistance, guidance, influence, or support in your creative effort in a way that reflects a copyright contribution. This issue was discussed in my answer to Are there cultural objects that came thanks to this site? That question and its answers would be good reading for you generally, especially the linked answer to my question about copyright and Stack Exchange over at Law.SE.
In this case, when it comes to copyright law, there are specifics you need to follow, none of which have been provided by Stack Exchange that I know of. Because everything posted on all Stack Exchange sites are licensed under CC-BY-SA (Creative Commons Attribution - ShareAlike), you are required to:
Attribution — You must give appropriate credit, provide a link to the license, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use. (Source, identical in V3.0 & V4.0).
But it sounds like this isn't at all what you're trying to do
Second, it sounds like what you're really trying to do is acknowledge Worldbuilding.SE, but not attribute copyright credit. In other words, you're simply expressing your gratitude. In this case, copyright and the law are no longer particularly relevant so long as how you refer to Stack Exchange would be deemed by Stack Exchange to be positive.1 In this case, you want to be intentionally vague. For example:
I would like to express my thanks to my friends at Worldbuilding.StackExchange.com, owned and operated by Stack Exchange, Inc., for their support, and to Stack Exchange, Inc. itself for hosting such a valuable resource.
How you say that is not as important as making sure "Stack Exchange, Inc." is used.
BTW, should you publish, I would recommend heading over to that question I linked to, Are there cultural objects that came thanks to this site?, and shamelessly answering it with, "Yeah! Here's one: my publication!"
1 My family owned a micro-publisher for ten years. Our experience with this is that most organizations have ways they would prefer to be referred to, e.g., "Stack Exchange, Inc." but they rarely care about the details unless what you say threatens a trademark or, basically, pisses them off. E.G., "My undying gratitude for the worthless help Coke gave me while writing this article." (Example is artificial, obviously.) While anybody can sue anybody for any reason, large companies generally won't slap small entities so long as they've been referred to legally. E.G., "Coke" becomes "Coca-Cola Consolidated, Inc." so that all they can complain about is your free speech. And I chose that example intentionally, because Coke officially changed its name back in 2019 and it's "your" job to keep up with changes like that.