My son is really into fantasy books. Loved the Belgariad. I find it tricky to find stuff without sex or other adult themes for him to read. Which makes the genre sound awful, I know.
Well, there’s no sex at all in Tolkien. Nor much in The Name of the Wind - which is excellent.
Maybe Lois McMaster Bujold, both her scifi and Five Gods books.
If he liked the Belgariad then perhaps Kate Elliot? There are a lot of them, with endless battle scenes.
Brandon Sanderson is excellent.
Raymond Feist - more battle scenes, not much sex, if any.
Mark Lawrence perhaps, his Prince of Thorns series.
Robin Hobb - I’m not a big fan, but lots of people are.
Barbara Hambly’s Time of the Dark books and the Sun Wolf books. Old school, but she’s a terrific writer.
Joe Abercrombie and Brent Weeks - I can’t remember the sex quotient of those.