If he has a DC Public Library card, have him use his card number and PIN to log into the NoveList database on the website. Input titles and authors he’s enjoyed into the search box and it will generate a list of read-alike suggestions based on appeal factors.

NoveList is great and not enough people know about it. I’m a children’s librarian and use it every day.

Anything by Ray Bradbury

Watership Down

Dungeon Crawler Carl

-seems ridiculous but actually good

Following - thank you for all of the suggestions!

Most recently, my 17DS read Killers of Flower Moon. He flew through it.

A previous poster recommended The Expanse series. I'd second that.

If your son enjoys the nuts-and-bolts blue-collar science fiction aspects of The Expanse, I'd also recommend Daniel Suarez's series Delta-V and Critical Mass (3rd book is planned). If the techno-thriller aspects of those appeal to him, I'd recommend Suarez's Daemon (and sequel Freedom (tm)).

Ready Player One

ERB Edgar Rice Burroughs in mid teens
Louis L'Amour in mid teens

Hemingway in late teens
George Orwell in late teens

Also Robert Heinlein if he likes dystopian scifi or steampunk stuff.

Recursion, by Blake Crouch (also Dark Matter and Upgrade by BC)
Last Days of Night, Graham Moore
American War, by Omar El Akkad
The Holdout, Graham Moore

The Expanse Series

First one is Leviathan Wakes.

You listed some historical fiction so, maybe Pompeii by Robert Harris.

Starter Villian and Kaiju Preservation Society by John Scalzi.
Seconding Murderbot.

The Magicians Trilogy by Lev Grossman
The Will of the Many

For something heavier, I read all of these at 18 (I'm female but read a lot of scifi):

Catch 22
Slaughterhouse Five
The Collector - this one gets some flack because it's disturbing but I think people are missing the point
The Things They Carried
Franny and Zooey
Brave New World


Also don't sleep on the recent classics like Jurassic Park and The Martian.