There's a pretty pervasive opinion and guideline that an agent doesn't generally look at an author's debut book if it is more than 95k+ words (at least from what I've read/been told). Helene Wecker's "The Golem and the Jinni" is about 145314 words, how is this possible as first time author? There are exceptions to the rule, of course, but there are many other examples I've seen of debut authors releasing considerably larger than expected word counts. Would love some insight on this!
I understand it's different depending on your genre, but I don't know the numbers on that. But yeah, essentially, they aren't willing to sink more cost into production and force readers to invest in a longer story from a untested and unproven author. You need to earn the right to write longer stuff. When you start selling at those Stephen King numbers you can dictate what you write and how long it is.
Like all rules, I imagine those cases are exceptions to the rule. Maybe the agent really liked/believed in the original manuscript. Maybe it might've been the author's debut novel, but they otherwise had enough of a social following that the agent felt safe with a long debut novel.
Did some research. She met her agent on some sort of mixer with agents arranged in her bachelors studies. So mainly she got access prior to the book even getting wrote.