The first paragraph of a novel chapter — should it be indented as other paragraphs or not? This is a question more for book designers than authors, but should be of interest to the latter. Moreover, some of us hold both jobs.
Some ‘experts’ will claim it should not be, that the professional approach is to align that first line fully left. That is certainly a common practice but I have looked over a rather large number of professionally printed novels from the past century and found that indenting is also common. I personally prefer to indent that first paragraph, to make it like every other paragraph — usually.
It really depends on what looks best on the page and, particularly, how it interacts with the titling elements. And sometimes it depends simply on personal preference. The one time we would definitely align left is when there is some other typographical difference from the following paragraphs, as when drop caps or small caps are used. Then, go left, most certainly; indenting those would look odd.
I generally avoid that sort of thing. Does it actually add anything to the reading experience? Yes, it can sometimes enhance the appearance of the page — and sometimes distract or even seem pretentious. It is also something else that can go wrong when the book goes to the printer, in a PDF to Print on Demand setup. That was not a consideration in the days of physical typesetting.
So there is no answer. Indent or don’t indent, as you feel proper. Change it up from one book to another (but keep those in a series consistent). And keep in mind that the reader comes first in any design decision.