Hi mummy
I am no expert - just a Mum - but we found sharing the reading on nights DD1 (who seriously struggled - finished KS1 NC L1 in reading) really helped.
At first DD1 would read words she knew: The, The End, Once upon a Time, Chip, Biff, Magic Key, said, and, or, but, etc.... and I'd read the rest.
But occasionally she'd read a whole sentence. In which case I'd read the rest of the paragraph.
Eventually she was regularly reading whole sentences and I was finishing the paragraph.
So we moved on to her reading a paragraph and I'd read the rest of the page or the next page.
Then her reading a page and I'd finish the chapter.
BUT....
We also read to her - we decided that her interests in reading material in Y3 exceeded her ability - so DH and I would read to her. In this way she could know about books friends were reading (Charlie in the Chocolate Factory, Charlotte's Web, Harry Potter series, Lemony Snicket series etc...) and enjoy higher quality fiction. It also meant that she wasn't afraid of 'longer books' - she had happily listened to us read 200+ page books and thoroughly enjoyed them. She's able to read quite well now (now Y6). It's been a long slow struggle and was seriously helped by support from a TA in Y4. But she's a strong reader now.
Just accept it's a bit of a dance - one step forward, two steps back, three steps forward, two steps back, etc....
However, when you're reading to your DC from a more challenging book at home, every now and then point to a word they can read and celebrate when they can. When you see that easy sentence to read. 'Frodo saw the ring' - and let them read it. My DD1 was over the moon when she read something along those lines from the Hobbit. She knew JRR Tolkein was a proper author (TOLKEIN was the name of top table for reading) - she was over the moon.
Learning difficulties complicates this of course - but it is a battle worth fighting. The prize is your DC can read prescriptions, forms, instructions, information leaflets, etc... - all crucial skills in the adult world.