I learned to read younger than most, and could read well, but never really liked it. My parents tried the things in the other replies you got, but none of it actually worked (reading to me in particular my mom is convinced did it, but she never realized I was mostly ignoring her and watching other kids play).
I actually remember specifically what it was: finding this book in the impulse-buy section of our local Walgreens when waiting at the checkout line at about 9 or 10 years old: https://animorphs.fandom.com/wiki/The_Forgotten
For some reason I was big into animals, so that cover really caught my eye. Up until that point I knew almost nothing about sci-fi, so this and the rest of the series was basically my introduction to the genre, which is still the majority of what I read.
So my basic advice is a bit vague but: find a book on a topic they'd like, with a relevant cover, and somehow position it so they discover it and curiosity takes over. Don't push it on them, they'll probably just assume it's something you like instead of something they'd like (which was the case for almost everything before I discovered sci-fi).
I actually remember specifically what it was: finding this book in the impulse-buy section of our local Walgreens when waiting at the checkout line at about 9 or 10 years old: https://animorphs.fandom.com/wiki/The_Forgotten
For some reason I was big into animals, so that cover really caught my eye. Up until that point I knew almost nothing about sci-fi, so this and the rest of the series was basically my introduction to the genre, which is still the majority of what I read.
So my basic advice is a bit vague but: find a book on a topic they'd like, with a relevant cover, and somehow position it so they discover it and curiosity takes over. Don't push it on them, they'll probably just assume it's something you like instead of something they'd like (which was the case for almost everything before I discovered sci-fi).