There are other Anne books too. Agatha Christie is a good shout for a different genre.
Dodie Smith as others have said and Jane Austen.
This is a good starting point
amp.theguardian.com/childrens-books-site/2014/mar/22/well-read-teenager-classic-books-for-teens-young-adults-twilight
we also devoured the school reading list and the school library is a gold mine!
very often the Book People, the works etc have classic novels as a pack, I brought some gothic novels etc
Mine devours books can often read one a day or every two days.
for humour she loves Cabin Pressure and Yes, Minister as audio etc but I’m very if the first 100 pages don’t grab you and you are reading for pleasure as opposed to ‘reading the classic’ for the sake of it be prepared to put it aside and read something else.
the woman in black is a good first darker book as is withering heights. Please excuse lack of capitals - stitches in my finger!
if you have a local library - ask! I must admit to going into Waterstones when she was much younger and saying ‘Help she’s a free reader- I think this was year 2’ and honestly they couldn’t of been more helpful.
There is a few books worth getting though one is the BBC 100 reads which is old now but useful to brush through to get ideas, we also have a teen book guide off Amazon and one I picked up years ago and well worth getting something like this as she often looks through and then gets ideas.
mine also loves the Week (adult one) as a magazine.
there is also a Facebook group called women who love reading great books which is a lovely nice calm group with loads of ideas - I like it as it pushes me out of my comfort read into other books.
just another thought - the song of Achilles and poetry can be a good shout and Mary beard etc
it nice to visit where the authors live etc as day trip out or cinema eg crawdads
sorry can you tell I’ve had similar over the years!