To try and find some good teens books that don't push the LGBTQ agenda?

Don't know what age S1 is. My 11 year old is really enjoying percy jackson books and there are tons of them ( I'm really enjoying them too)

I work in a secondary school library. There are a huge number of books published for teens , there is a massive difference between books that have a range of characters with different love interests like Percy Jackson and those stories where it is all about being gay or trans. Too many to name!
Our most poplar books are wimpy kid and manga, heartstoppers which is a love story between two boys who are 15/16 and the cherub series which starts with the Recruit.
I bought Malory Towers and St Clares and they have a niche following.
I love the Dark is Rising series by Susan Cooper, the children and teens in those books are too busy fighting evil to be interested in each other.
And special shout to for the Hunger Games and the Noughts and Crosses series and the Crongton series by Alex Wheatle. All special favourites of mine. I find younger teens really enjoy gore and moralistic stories.

Anything with a publication date from before the mobile phone era. So pre 2000 should be quite safe without compromising quality.

What does she like -
Real life
Historical
Fantasy
Sci fi
I liked books like Goodnight Mr Tom, Little House on the Prairie, Anne of Green Gables at that age.

Maybe go back a couple of decades and search older young adult fiction?

as a bisexual teen & avid reader I rarely encountered any queer characters.

still was and turned out bi. Just confused and neurotic about it until wider culture relaxed.