I'm writing my first novel and I wanted to try and write around 12-15 chapters about 10k-ish (give or take a thousand or two) words each. The idea behind it being each chapter covers a very large arc in the story. Should I split this into more smaller chapters? Or is it okay to go big like this?
That is not particularly "big", and it is fine. (--added-- for what it is worth, chapters are generally 3000 to 5000 words long, but it is not a rule. The link goes into more details and examples.)
A chapter is usually related to a setting, (which may be moving; e.g. two people walking somewhere, or people on a train). Or is about a particular form of character interaction, a meeting or joint action of some sort. Then that chapter concludes, and the next chapter is a different setting, different set of characters interacting (even if the MC is in all of them), different goals.
Depending on how you write, they can be long or short.
Chapters can have arcs, I am not sure what you mean by "covers a large arc in the story". Typically chapters would not have overlapping time lines, that would be a difficult novel to follow. For example, if CH-1 covers 1980-1987 for a character, and CH-2 covers 1981-1984 for another, etc. It would be hard to remember what was going on in 1981 in CH-1 when we are reading about 1981 in CH-2. Most novels, chapters appear in chronological order without overlap.
I would judge it chapter by chapter. For example one chapter might feel wordy and heavy with story details so you could break that chapter into two chapters so it changes the pace and gives the reader a chance to breathe. For myself I write around 8000 words per chapter, but once again if I read it and feel it drags on a bit I'll cut parts out or make it into two chapters and reread and see if it flows any better. Finally I would say write the novel start to finish without worrying about the chapters till you finish the whole book. Otherwise it can slow down or completely stop you from writing the book if you worry about editing or structure during your first draft. Great question. Hopes this helps.