Jack Shaftoe,aka The King of the Vagabonds, Half-Cocked Jack, l’Emmerdeur, Quicksilver, Jack the Coiner…

The Baroque Cycle, Neal Stephenson

Yes it is. Per the Wikipedia article: “It is set after the Second Afghan War (which ended in 1881), but before the Third (fought in 1919), probably in the period 1893 to 1898”

Well, it’s more than just the use of “thou/thee”, which are just prominent examples in a style that seems to me anachronistic for the time period of the book. Here’s a longer sample

“To what, child?” said the lama.
“God knows, but so my father told me. I heard thy talk in the Wonder House of all those new strange places in the Hills, and if one so old and so little⁠—so used to truth-telling⁠—may go out for the small matter of a river, it seemed to me that I too must go a-travelling. If it is our fate to find those things we shall find them⁠—thou, thy River; and I, my Bull, and the Strong Pillars and some other matters that I forget.”

But maybe this fomral/informal distinction proposed with respect to “thou/thee” is extended to the rest of the dialogue.

I’m saying that this style of speech was archaic by time of its writing and publication. It was not appropriate to time and place in England for sure. It may have been in India, but I doubt it.

Neal Stephenson

“No insect hangs it’s nest on threads as frail as those which will sustain the weight of human dignity.”

Edith Wharton The House of Mirth

(I was absolutely wowed with her prose in this book.)