I think that the first thing you should do is clarify the theory that you are going to expose, because the author of a novel knows that he must be prepared to defend, as a first thing, the very coherence of the novel in terms of fulfilling the premises of the novel. the plot, mainly that the conflict of the story is resolved, a certain evolution of the characters is appreciated (the path of the hero is by far one of the most addressed treatments in most stories) and there are no formal contradictions within the text same as confusing the timeline of the story or getting the names of characters wrong, for example. So, figure out if the underlying philosophical thought in your story is also controversial or not well exposed or even easy to attack by the eternal nerds of the fandom. That they are legion, they are usually very well informed about almost everything and are especially fierce with every detail.
Then, in the manner of Descartes, organize this information well, for which I suggest that you divide it into doses and study how it can be inserted into the text of the novel, either through proverbs, jokes (the wisdom of humor is certainly impressive) and, as far as possible, avoid dialogues in which one character expresses a philosophical concern and a second character actually releases a true theoretical discourse that, deep down, is nothing more than the author himself speaking but also one of the errors that with greater speed it makes the readers flee. As a side note, this problem is also experienced by the authors of hard fiction who have no greater knowledge of science fiction or less of fantasy but instead have abundant scientific theory and believe that it is enough to fill pages of it without noticing that they are boring, and incredibly, to the poor reader.
For the rest, this philosophical ramblings in novels are not so unusual. Take, for example, what Michel Houllebecq does in particular in
Atomised. However, this type of novel is also often known as the literature of ideas and one of its characteristics is that they are heavy books with little dialogue and action, since obviously the supposed suspension of disbelief, that pact that is established between author and reader, it assumes that the exposure (what elsewhere they call data dumps) will be the constant. Something that, in my opinion, is not so typical of fantasy novels, since they use more the sense of wonder, they obviously portray exotic worlds (which requires dedicating space for their corresponding presentation or description) and in reality the action , intrigue and adventure are the keynote. Which leads me to think that a fantasy story may not be the most appropriate format. In addition, fantasy is usually pigeonholed into a rather YA audience.